What do you call atoms that have gained or lost electrons? | Reference.com What do you call atoms that have gained or lost electrons? A: Quick Answer Atoms that have gained or lost electrons are called ions. If an atom gains electrons, it is called an anion; if it loses electrons, it becomes a cation. Through the gain or loss of electrons, atoms are no longer neutral. Full Answer When atoms gain electrons, they become negatively charged. Atoms losing electrons become positively charged. In a neutral atom, the number of electrons orbiting the nucleus equals the number of protons in the nucleus of the atom. Protons are the positive particles in an atom, while electrons are the negative ones. A neutral atom has the same number of positive as negative charges. With the positive and negative charges canceling each other out, a neutral atom has no net charge. With the gain or loss of electrons, the balance of protons and electrons is shifted. Either the atom contains more protons than electrons or more electrons than protons, resulting in the atom gaining a net charge.

Atoms, Electrons and Photons - EnergyGroove.net EnergyGroove.net A positively charged atomic element Neutron A neutrally charged atomic element Nucleus The center of an atom, composed of the proton(s) and the neutron(s) Electron A negatively charged atomic element that orbits the nucleus Electron shell The orbital level(s) that an electron can occupy Electromagnetic force One of the four fundamental forces of nature that binds electrons to the nucleus Photon The basic unit of light and the force carrier for the electromagnetic force Ion An atom that has either gained or lost an electron, causing the atom to become either negatively or positively charged, respectively Electrons Electrons are often represented as orbiting the nucleus, but in reality their movement is more complex and they are considered to move about in an “electron cloud”, which exists around the nucleus. Within the electron cloud there are different shells (energized levels) that an electron can occupy. A stable atom has an equal number of protons, neutrons and electrons. As such it has a neutral charge.

There has been debate about charge assignment, see the following article about conventional flow notation versus electron flow notation: Electron Pairs Electron configuration in most atoms involves electron pairs, i.e., two electrons occupying the same shell level, as opposed to just one electron, a state which also exists. In an electron pair each electron has an opposite spin to the other, which causes them to cancel out each other’s magnetic influence and creates magnetic neutrality for the atom. Calcium atom Valency and Valence Electrons “The outermost orbital shell of an atom is called its valence shell, [and the electrons there are called valence electrons]. Valence electrons are the highest energy electrons in an atom and are therefore the most reactive. While inner electrons (those not in the valence shell) typically don’t participate in chemical bonding and reactions, valence electrons can be gained, lost, or shared to form chemical bonds. For this reason, elements with the same number of valence electrons tend to have similar chemical properties, since they tend to gain, lose, or share valence electrons in the same way. The Periodic Table was designed with this feature in mind.

Each element has a number of valence electrons equal to its group number on the Periodic Table.” 1 Free Electrons Electrons in the outermost valency shell are the furthest from the nucleus and therefore have the weakest attraction to it. In certain conditions the outermost valency electron is so loosely bonded to the atom, e.g., the copper atom, that it is free to randomly wander from one atom to another. This creates free electrons. When the random movement of free electrons is controlled by an external influence, e.g., a magnet, the free electrons can be directed to form an electrical current. Copper atom Molecular Bonding The electron is responsible for chemical bonding where electrons are shared between atoms to create molecules. There are two types of bonding, covalent and ionized. Covalent bonding involves atoms sharing valency electrons, usually in atoms which have only one electron in their valency shell, and so seek stability by adopting a second electron, in this case by sharing it with another atom that also seeks this stability. Water molecule Ionic bonding involves one atom losing an electron to another atom. The first becomes a positively charged ion and the second becomes a negatively charged ion.

This charge difference creates an attraction between the two ions and they join to form a bond. Sodium chloride molecule (salt) Light and Photons “An electron has a natural orbit that it occupies, but if you energize an atom you can move its electrons to higher orbitals [shells]. A photon of light is produced whenever an electron in a higher-than-normal orbit falls back to its normal orbit. During the fall from high-energy to normal-energy, the electron emits a photon — a packet of energy — with very specific characteristics. The photon has a frequency, or color, that exactly matches the distance the electron falls.” 1 The reverse process, i.e., when an electron moves to a higher orbital (shell), happens when a photon impacts with an atom, i.e., the atom absorbs external energy. Currently light is known as being of wave forms called fields and particle forms called photons.

Field (wave) properties include: 1 electric field (wave) 1 magnetic field (wave) Each field (wave) is perpendicular to the other and both are perpendicular to the direction of movement (see below image) Photon properties include: No magnetic charge A speed Angular momentum (like a gyroscope) with spin axis parallel or anti-parallel to its direction of movement Light travels as photon particles that also create a field-wave of electromagnetic radiation, i.e., it is photo-electromagnetic energy. Photons carry energy (photon energy) relative to their frequency (wavelength) of light, where, for example, red light, which has a long wavelength, has low photon energy, and ultra-violet light, which has a much shorter wavelength, has higher photon energy. When photons hit matter, several things can happen depending on the amount of photon energy and the type of matter hit. See video below. The photons can be reflected or scattered off the object. The photons can be absorbed by the object. The photons can be refracted through the object. The photons can pass through the object with no effect. This behavior is important for understanding solar panel technology (see Solar Panels article) .

Links Basic Chemistry: Atoms and Ions LESSON 1: Basic Chemistry Atoms & Ions | Chemical Bonding | Water | Acid & Bases | Organic Compounds | Carbohydrates | Lipids | Proteins | Enzymes | Nucleic Acids | ATP This lesson will introduce you the student to basic chemistry principles. An understanding of this basic information will allow you to learn the more advanced topics in your course lectures. This lesson focuses on a number of areas related to basic Chemistry. You should review each page in order as they build upon one another. Many of these topics will be review. Others may be new to you. Either way you will learn the fundamentals of chemistry needed in this course. ATOMS AND IONS Atoms are the basic unit of chemistry. They consist of 3 smaller things: Protons - these are positively charged (+) Electrons - these are negatively charged (-) Neutrons - these have no charge These 3 smaller particles are arranged in a particular way. In the center is the Nucleus where you find the positive Protons and neutral Neutrons. In orbit around the nucleus are the Electrons.

These are found in a series of orbits (depending on the atom) with differing numbers of electrons as seen below. Interaction of Atoms It's the electrons in orbit around the nucleus that allow one atom to interact with other atoms so they can be linked together. For example, H2O consists of an Oxygen atom linked to 2 Hydrogen atoms. The linkage or interaction between the electrons of the Hydrogen and Oxygen atoms is called a Chemical Bond. More on these later. Atoms in the Human Body The human body is made up of a couple dollars worth of chemicals. The 12 most useful atoms for you to know about are listed below: Ions Sometimes atoms gain or lose electrons. The atom then loses or gains a "negative" charge. These atoms are then called ions. Positive Ion - Occurs when an atom loses an electron (negative charge) it has more protons than electrons. Negative Ion - Occurs when an atom gains an electron (negative charge) it will have more electrons than protons. The following image shows Na losing an electron and Cl gaining an electron Thus the Na becomes Na+ The Cl becomes Cl- Biochemistry.

Atoms An atom that has either gained or lost an electron is called an Ion CONSERVATION OF MASS – –Things can move / change position. But. - ppt download Download Presentation is loading. Please wait. Biochemistry. Atoms An atom that has either gained or lost an electron is called an Ion CONSERVATION OF MASS – –Things can move / change position. But. Published by Silas Robbins Modified about 1 year ago Embed Similar presentations More Presentation on theme: "Biochemistry. Atoms An atom that has either gained or lost an electron is called an Ion CONSERVATION OF MASS – –Things can move / change position. But."— Presentation transcript: 1 Biochemistry 2 Atoms An atom that has either gained or lost an electron is called an Ion CONSERVATION OF MASS – –Things can move / change position. But ALL the mass that is available is ALL the mass that will ever be available.

Periodic Table –Mass Number – how much it weighs in grams –Atomic Number – location on the periodic table (number of protons) –Isotopes – variations in elements based on number of neutrons 3 Atomic Mass = # Protons + # Neutrons The atomic mass of carbon = 12 The atomic # of carbon = 6 = the # of protons # neutrons = Atomic Mass - # protons # neutrons = = 6 4 s- block d- block (n-1) p- block f- block (n-2) Label your Periodic Table 5 Compound-2 or more elements combined chemically –A compound is made up of different elements –The smallest particle of a compound with independent existence is: The molecules of that compound Ex: A CO 2 Molecule as opposed to millions of CO 2 Molecules 6 Nobel Gases: always have their outside electron shell full: They never bond with other atoms 7 Covalent Bonds: When Atoms share electrons in their outer energy levels: O 2H 2 0 8 Ionic Bonds: an electric attraction between two or more differently charged atoms or groups Atoms that have gained or lost an electron are called ions.

NaClHCl 9 Properties of Matter Physical Properties –Properties that do not change the chemical nature of matter Examples –Color, Smell, Freezing Point, Boiling Point, Melting Point, Polarity, and Density –Physical change – change in its state 10 Properties of Matter Chemical Properties –Properties that DO change the chemical nature of matter Examples –PH, Combustion, reactivity with water, explosions! –Compounds put together that create a new compound 11 States of Matter Physical Changes –Solid, Liquid, Gas Chemical Changes –Changes properties of matter all together Ex. Spoiling Milk 12 Properties of Chemical Change Forms or breaks chemical bonds Energy is taken (endothermic) or energy is released (exothermic) One or more new chemical substances are formed The process is usually difficult to reverse 13 Examples of Chemical Change Digestion Photosynthesis Respiration Burning Decomposition 14 Structure of Atoms Protons: –A sub atomic particle that is located in the nucleus and has a positive charge Neutron: –A sub atomic particle that is located in the nucleus and has a neutral charge Electron: –The smallest of the subatomic particles that carry a negative charge and surround the nucleus.

15 Energy and Chemical Change Any energy an object has because of its position is called Potential energy. The energy in motion (actual) is called Kinetic energy. 16 Atoms Electrons circle the nucleus in the electron shell Noble gases all have there outer most electron full of electrons. 17 18 19 Mixtures Solution –Homogenous (same) mixture of components that stay mixed Sugar and water Suspension –Mixture of two substances that may mix right away, but do NOT stay mixed up Starch and water 20 Mixtures Colloid –A suspension of small particles that are dispersed into another substance Partial Mix 21 Types of Bonds Cation- –A positivily charged ion (more protons than electrons) Anion – –Negatively charged ion that contains more electrons in its outer shell compared to the protons. 22 Bonds Ionic Bond –Sending an electron to an atom that is positively charged (opposing charges attract) EX. –Na (+) = Cl (-) »Salt –H (+) = Cl (-) »Hydrochloric Acid 23 Bonds Covalent Bonds –Sharing of electrons for the benefit of both EX.

–O2 –H20 24 Bonds Hydrogen –Weaker bond It is the type of bonds that hold our DNA molecules together. –Must include a Hydrogen molecule –Also, usually attaches to a electronegative atom 25 Properties of Water Polarity of water –Water is made up of two polar covalent bonds, but the molecule has no overall net charge –Oxygen slightly negative (heavier) –Hydrogen slightly positive (lighter) Allows for cohesion of other water molecules 26 Properties of water Temperature stabilizing effects –Water is warm – hydrogen electrons move about and break leading to evaporation –Water is cold – Hydrogen molecules get closer together and form a lattice (solid) structure that we know as ICE 27 Properties of water Water Cohesion- –Water molecules binding to other water molecules Hydrogen bonds attracted to each other and stick together! –Ions and polar molecules easily dissolve in water. The water molecules surround and separate the solute being dissolved. 28 Acids, Bases, and Buffers pH – “Potential Hydrogen ions”.. –Measurement of how many concentrated H+ ions there are.

1 – very acidic 14 – very basic 7 – Neutral 29 Acids – donate H+ to a solution increasing the conc. of H+ in the solution Bases – Absorb / accept H= and they lower their concentration in the solution Buffers – Are compounds that help absorb or donate H+ at the appropriate time as to keep a solution balanced Salts – Can be formed by the combination of a strong acid and a strong base Acids, Bases, and Buffers 30 Carbon Compounds All life organisms are made up of Carbon –Organic Molecules Organisms consist mostly of which atoms? –Carbon, Nitrogen, Hydrogen, Oxygen, Phosphorous, trace elements 31 Chemistry of Carbon Carbon has how many bonds? –How many valence electrons does carbon have? Carbon can bond to 4 other molecules Carbon can form a single, double, or triple bond 32 Functional Groups of Carbon A chain of carbon and hydrogen is called a hydrocarbon. –EX. Methane, Ocatane Just C and H There is ENERGY in these bonds!!! Do you recognize the molecules?

33 Other important carbon based groups: Hydroxyl Group: –OH Carboxyl Group: –COOH Amino Group: –NH 2 or NH 3 Phosphate Group: –PO 3 or PO 4 34 Hydroxyl –OH –organic compounds with OH = alcohols –names typically end in -ol ethanol 35 Carboxyl –COOH –C double bonded to O & single bonded to OH group compounds with COOH = acids –fatty acids –amino acids 36 Amino -NH 2 –N attached to 2 H compounds with NH 2 = amines –amnio acids NH 2 acts as base –ammonia picks up H + from solution 37 Phosphate –PO 4 –P bound to 4 O connects to C through an O PO 4 are anions with 2 negative charges function of PO 4 is to transfer energy between organic molecules (ATP) 38 How do cells build organic compounds?

Reactions: the use of raw materials “atoms”, energy, and enzymes to do one of the following –Functional group transfer – One molecule gives up a functional group which is then attached to another molecule –Electron transfer – One or more electrons is stripped from one molecule and donated to another molecule –Rearrangement – A juggling of internal bonds converting one type of organic compound into another –Condensation (Hydrolysis) – the removal or addition of water to create new bonds and break existing ones –Cleavage – A molecule splits into two smaller ones. 39 Important construction terms Monomer : a molecule that is building block for something larger Dimer : two monomer stuck together Polymer : more than two monomers stuck together Dehydration : Pulling water out of two molecules so as to bind them together Hydrolysis : Adding water to a molecule to break it apart 40 Carbohydrates Contain – Carbon, Hydrogen, and Oxygen in a 1:2:1 ratio –Example: Glucose (C 6 H 12 O 6 ) The monomers that make them up are called monosaccharides 41 What are Carbs used for?

Uses – Energy, Structure, Signals These monomers usually form a ring structure, especially in water. –Examples Glucose and Fructose 42 Carbohydrates When do you notice about glucose and fructose? –They have the same number of atoms but they are in a different arrangement. They are called isomers –The condensation of two monosaccharides is called a disaccharide. Example - Sucrose 43 Carbohydrates The largest carbohydrates are starches 44 Carbohydrates The reaction that breaks down complex molecules – reverse condensation is called hydrolysis. –We have an enzyme in our body to do this process Amylase (found in saliva) –New Study in sleep deprivation 45 Starch VS. Cellulose We can break down starches, but our body cannot break down cellulose.

46 Tests for Carbohydrates TESTMonosaccharidesDisaccharidesPolysaccharides IodineNo Change Turns Black Benedicts Solution Color changes with heat No Change 47 Lipids Lipids contain –Carbon, Hydrogen, and Oxygen EX – Fats, Phospholipids, waxes, sterols “Steroids” 48 Lipids They are used in living things for energy storage, structural molecules, and signaling molecules Basic Structures –Tail and Head 49 Triglycerides 50 Saturated Fats: Only form single bonds with Carbon Atoms: No room for more hydrogen atoms Unsaturated Fats: Form double bonds in Carbon atoms 51 All lipids are insoluble in water – A good test? Water Solubility Paper smear test 52 Phospholipids Found in the cell membrane 53 Cell Membrane 54 Test for Fats TESTFATNOT A FAT Brown PaperPaper Changes (transparent) Dries the same Water Solution They separate They Mix 55 Proteins Proteins are made up of: –Carbon, Hydrogen, Oxygen, & Nitrogen Ex.

– Eggs, seeds, hair, and meat –Basic Monomers – Amino Acids (aa) 56 Amino Acids (aa) Each aa is going to contain four distinct groups –Carboxyl Group – COOH –Amino Group – NH3 –R Group (20 different R groups) –A Hydrogen atom – H If there are twenty different amino acids 57 Protein Structure Through a series of dehydration reactions, aa are joined into a chain to form a protein.

A special bond is formed –Peptide Bond Polypeptide – polymer of aa 58 59 Protein Structure When you have two aa together –Dipeptide Three or more aa –Polypeptide These are used by living organisms for: Enzymes, structures, transport, and signaling 60 3D structure of proteins Level 1 Level 2 Level 3 Level 4 61 62 Proteins DENATURATION Is the breaking down of molecules Other molecules can be attached to proteins –Glycoproteins and Lipoproteins 63 Test for Proteins: Xanthopoetic test TESTPROTEINNOT A PROTEIN Nitric AcidTurns YellowNo Color Change 64 Enzymes A chemical that speeds up a reaction is called a –Catalyst Proteins that do this process are called –Enzymes Ex. – Sucrase, Amylase, Lactase 65 Nucleic Acids All instructions for cellular activity are in the Nucleic Acids –Two kinds of Nucleic Acids DNA –Holding genetic information –Where is it found? »In nucleus on chromosomes RNA –Holding info for building proteins –Where are they found?

»Everywhere in a cell 66 What makes them up? Complex monomers – Nucleotides Bonds between them are called phosphodiester bond –Formed by a phosphate Ionic bonding Ionic bonding According to our crude, conceptual definition, chemical bonds can form either by electron transfer between atoms or by sharing of electrons. The former case constitutes a kind of bond known as an ionic bond. The reason for this is that if one atom transfer electrons to another, the donor is left with a net positive charge, while the acceptor is left with a net negative charge. According to Coulomb's law, these charged species should attract each other, and this attraction is what stabilizes the bond. When atoms lose or gain electrons, they become what are called ions. Loss of electrons leaves an atom with a net positive charge, and the atom is called a cation. Gain of electrons leaves an atom with a net negative charge, and the atom is called an anion. Some examples are: Special stability results when an atom, by losing or gaining electrons has as many valence electrons as a noble gas atom. In this case, we say that an atom or ion has a completed octet.

Na has as many electrons as Ne, which explains why it loses only 1 electron, while Ca also has as many electrons as Ne, but since it is a Group II, element, it must lose 2 electrons to achieve an octet configuration. The basic assumption of the Lewis model is that atoms will tend to form chemical bonds in order to complete their valence shells and achieve completed octets (or doublets in the case of H and He). This is known as the octet rule. Consider the loss of an electron by sodium: By losing the electron, Na achieves octet stability, since Na is isoelectronic with Ne. Similarly, chlorine favors gaining an electron: Thus, Na can donate an electron, which Cl can accept and an ionic bond can form between them. This is expressed chemically as which is a molecule of sodium chloride. Atoms that can lose two electrons, such as Calcium, can form molecules with two chemical bonds: In transition metal atoms and in many heavier elements, the octet rule does not apply.

Examples: Ions: Atoms with an Electrical Charge - dummies Ions: Atoms with an Electrical Charge Ions: Atoms with an Electrical Charge Ions: Atoms with an Electrical Charge Atoms (or groups of atoms) in which there are unequal numbers of protons and electrons are called ions. Usually, the number of protons and electrons in atoms are equal. But there are cases in which an atom can acquire an electrical charge. An ion example For example, in the compound sodium chloride — table salt — the sodium atom has a positive charge and the chlorine atom has a negative charge. The neutral sodium atom has 11 protons and 11 electrons, which means it has 11 positive charges and 11 negative charges. Overall, the sodium atom is neutral, and it’s represented like this: Na. But the sodium ion contains one more positive charge than negative charge, so it’s represented like this: This unequal number of negative and positive charges can occur in one of two ways: An atom can gain a proton (a positive charge) or lose an electron (a negative charge). Cations and anions So which process is more likely to occur?

In general, it’s easy to gain or lose electrons but very difficult to gain or lose protons. So atoms become ions by gaining or losing electrons. And ions that have a positive charge are called cations. The progression goes like this: The sodium ion shown above is formed from the loss of one electron. Because it lost an electron, it has more protons than electrons, or more positive charges than negative charges, which means it’s now called the: Likewise, when the neutral magnesium atom loses two electrons, it forms the: Now consider the chlorine atom in sodium chloride. The neutral chlorine atom has acquired a negative charge by gaining an electron. Because it has unequal numbers of protons and electrons, it’s now an ion. And because ions that have a negative charge are called anions, it’s now called the: Other details about ions Here are some extra tidbits about ions: You can write electron configurations and energy level diagrams for ions. The neutral sodium atom (11 protons) has an electron configuration of: The sodium cation has lost an electron — the valence electron, which is farthest away from the nucleus (the 3s electron, in this case).

The electron configuration of the sodium ion is: The electron configuration of the chloride ion is: This is the same electron configuration as the neutral Argon atom. If two chemical species have the same electron configuration, they’re said to be isoelectronic. The preceding examples are all monoatomic (one atom) ions. But polyatomic (many atom) ions do exist. The ammonium ion is a polyatomic ion, or, specifically, a polyatomic cation. It is written as: The nitrate ion, is also a polyatomic ion, or, specifically, a polyatomic anion. It is written as Ions are commonly found in a class of compounds called salts, or ionic solids. Salts, when melted or dissolved in water, yield solutions that conduct electricity. A substance that conducts electricity when melted or dissolved in water is called an electrolyte. Table salt — sodium chloride — is a good example. On the other hand, when table sugar (sucrose) is dissolved in water, it becomes a solution that doesn’t conduct electricity. So sucrose is a nonelectrolyte. Whether a substance is an electrolyte or a nonelectrolyte gives clues to the type of bonding in the compound.

If the substance is an electrolyte, the compound is probably ionically bonded. If it’s a nonelectrolyte, it’s probably covalently bonded. Chemical Bonding Chemical Bonding Ionic Bonding We have learned that atoms tend to react in ways that create a full valence shell, but what does this mean? Sodium (Na), for example, has one electron in its valence shell. This is an unstable state because that valence shell needs eight electrons to be full. In order to fill its valence shell, sodium has two options: Find a way to add seven electrons to its valence shell, or Give up that one electron so the next lower energy shell (already full) could become its new valence shell. Which do you think is more easily accomplished? Right, giving up one electron! Atoms like sodium, with only one or two electrons in a valence shell that needs eight electrons, are most likely to give up their valence electrons to achieve a stable state. All these atoms need is another atom that can attract their electrons! An atom such as chlorine (Cl), that contains seven electrons in its valence shell, needs one more electron to have a full valence shell.

If we use the same logic as we did for sodium, we should conclude that chlorine would rather gain one more electron than lose all seven of its valence electrons to achieve stability. Under the right conditions, atoms like chlorine will steal an electron from nearby atoms like sodium. This ability to pull electrons away from other atoms is termed electronegativity . Atoms with a valence shell that is almost full are more likely to be electronegative because they have greater reason to pull electrons towards them. Electronegative atoms are not negatively charged, but they are more likely to become negatively charged. When an electron moves from one atom to another, both atoms become ions . An ion is any atom that has gained electrons to have a negative charge ( anion ) or lost electrons to have a positive charge ( cation ). An easy way to remember that a cation has a positive, or +, charge is to think of the letter t in the word cation as a + sign. Once an atom becomes an ion, it has an electrical charge. Ions of opposite charge are attracted to one another, forming a chemical bond , an association formed by attraction between two atoms.

This type of chemical bond is called an ionic bond because the bond formed between two ions of opposite charge. The sodium cation (Na+) and the chlorine anion (Cl-) are attracted to one another to form sodium chloride, or table salt. Although ionic bonds are very strong, they can be relatively easily broken if another attractive ion (or polar molecule) comes around. An ionic bond is formed when two ions of opposite charge come together by attraction, NOT when an electron is transferred. Think of ionic bond formation as the second step in a two step process: Two atoms each become ions. The atoms could have become ions in previous reactions with other atoms or the atoms may have reacted with each other, transferring the electron(s) from one to the other. The two ions of opposite charge “see” one another and become attracted enough to form the bond. Ionic Bonding This video visually illustrates how atoms form ionic bonds. Please enable iFrames to view this content or visit <a href="/html5/kalturaBig.php?id=0_9jcs473n" target="_blank"> Ionic Bonding Video </a>.

Please enable iFrames to view this content or visit <a href="/html5/biology/lesson2/Bio02_8_2ionicBonds.html" target="_blank"> Interactive Activity</a>. Covalent Bonding In ionic bonding, we looked at atoms with either one or two electrons in their valence shell and atoms that only needed one or two electrons to fill their valence shell. What happens when an atom, carbon (C) for example, has four valence electrons? Carbon would need to either lose four electrons or gain four electrons in order to have a full valence shell. Both of these situations would cause carbon to have a very strong charge, which would probably make it as unstable as having an incomplete valence shell! For atoms like carbon, there is another option: sharing. When two atoms each need additional electrons to fill their valence shells, but neither is electronegative enough to steal electrons from the other, they can form another kind of chemical bond called a covalent bond . In covalent bonds, two atoms move close enough to share some electrons. The electrons from each atom shift to spend time moving around both atomic nuclei.

In the most common form of covalent bond, a single covalent bond, two electrons are shared, one from each atom’s valence shell. Double covalent bonds where four electrons are shared, and triple covalent bonds where six electrons are shared, are also commonly found in nature. How do we know if and when covalent bonds will form? Atoms will form as many covalent bonds as it takes to fill their valence shell. This means that carbon, our previous example, will need to form four covalent bonds in order to fill its outermost shell. In each of the four bonds, carbon will contribute one electron and the other atom will contribute one electron, supplying carbon with eight electrons effectively orbiting its nucleus. Atoms like oxygen (O) will form two covalent bonds because they already have six valence electrons and only need two more electrons obtained by sharing. Put another way, oxygen shares two of its six valence electrons in covalent bonds while keeping four valence electrons for itself (4 unshared oxygen electrons + 2 shared oxygen electrons + 2 shared electrons from the other atoms = 8 total electrons).

In shell models , the shared electrons are shown within the overlapping region of the valence shells to represent the fact they are shared, but the electrons are actually moving around both nuclei and could be found anywhere around either nucleus at a given time. For simplicity, we often draw covalent bonds as straight lines between atoms to represent the structural formula . Each line represents a single covalent bond (two shared electrons), so double lines represent a double covalent bond (four shared electrons). Covalent bonds are usually found in atoms that have at least two, and usually less than seven, electrons in their outermost energy shell, but this is NOT a hard and fast rule. Hydrogen, for example, is a unique atom that bears closer examination. Because hydrogen only has one electron surrounding its nucleus, its valence shell is the first energy shell, which only needs two electrons to be full. Hydrogen tends to form covalent bonds because a single covalent bond will fill its shell. However, the one-proton nucleus is very weak and has trouble keeping the shared electrons around the hydrogen atom for very long. Covalent Bonding This video visually illustrates how atoms form covalent bonds.

Please enable iFrames to view this content or visit <a href="/html5/kalturaBig.php?id=0_jlwl604i" target="_blank"> Covalent Bonding Video </a>. Please enable iFrames to view this content or visit <a href="/html5/biology/lesson2/Bio02_10A_page3A.html" target="_blank">Check Your Understanding </a>. Other Kinds of Bonding When a covalent bond forms between atoms of similar electronegativity, the shared electrons tend to spend equal time around each nucleus. What happens if a bond is formed between atoms like oxygen, which is highly electronegative, and hydrogen, which is not? The oxygen atom tends to pull the shared electrons over to its side of the bond more often than the hydrogen atom does, resulting in polarity , or a partial separation of charge between atoms. The electrons don’t actually leave the less electronegative atom, but they do spend less time on that side. This results in two poles, one slightly positive and one slightly negative. This is called a polar bond, while covalent bonds where electrons are shared equally are called nonpolar .

Polar covalent bonds are the source of an additional kind of association called a hydrogen bond . In a hydrogen bond, the partially positive end of a polar covalent molecule is attracted to the partially negative end of another polar covalent molecule. For example, water is composed of two hydrogen atoms covalently bonded to a single oxygen atom. In a container full of water molecules , the hydrogen atoms of each water molecule are attracted to the oxygen atoms of other water molecules, forming hydrogen bonds between all of the molecules in the container of water. Hydrogen bonds are weak compared to covalent bonds, but they are strong enough to affect the behavior of the atoms involved. This leads to many important chemical properties in water and other molecules. Gaining and Losing Electrons Gaining and Losing Electrons Next, let's review two atomic properties important to bonding that are related to the position of the element on the periodic table. They are the tendency or ability of atoms to lose electrons and the tendency or ability to gain electrons. First, let's consider the ability to lose electrons. This is related to ionization energy, which you studied in a previous lesson.

The ionization energy, of course, is the amount of energy that it takes to remove an electron from an atom. You have learned that the ionization energies are lowest for the elements down and on the left hand side of the periodic table and increase as you go up and all the way across to the right including the inert gases. The ionization energy measures how hard it is to lose or remove an electron. High ionization energy means that it is hard to lose electrons. Low ionization energy means that it easy to lose electrons. The elements on the left side lose their electrons fairly easily and the elements on the right side of the periodic table do not lose their electrons very easily. Taking vertical position on the table into account, the elements that are lower on the table lose electrons more easily and the elements that are higher have a harder time losing electrons. Thus the overall trend is from most easily losing electrons on the lower left to least easily losing electrons on the upper right. Keep that trend in mind. Ability to Lose Electrons Answers Hopefully you had little or no problem with these. If you did, please check with the instructor. 1. The phrases "hard to lose electrons" and "easy to gain electrons" are both similar and different.

Comment on how they are similar as they pertain to elements on the periodic table. Comment on how they are different. Generally, elements that find it hard to lose electrons do so for reasons that also make it easy to gain electrons (high effective nuclear charge and low number of energy levels). The exceptions to this generality are the inert gases which find it both hard to lose electrons (because of high effective nuclear charge) and hard to gain electrons (because of a full outer energy level). --Note: there are a variety of correct ways to respond to this question. 2. In each of the following sets, select the element that will most easily lose electrons. Na Ions and Ionic Bonds About Watch and Favorite Watch Watching this resources will notify you when proposed changes or new versions are created so you can keep track of improvements that have been made. Favorite Favoriting this resource allows you to save it in the “My Resources” tab of your account. There, you can easily access this resource later when you’re ready to customize it or assign it to your students. Ions and Ionic Bonds Ionic bonds are attractions between oppositely charged atoms or groups of atoms where electrons are donated and accepted.

Learning Objective Predict whether a given element will more likely form a cation or an anion Key Points Ions form from elements when they gain or lose an electron causing the number of protons to be unequal to the number of electrons, resulting in a net charge. If there are more electrons than protons (from an element gaining one or more electrons), the ion is negatively charged and called an anion. If there are more protons than electrons (via loss of electrons), the ion is positively charged and is called a cation. Ionic bonds result from the interaction between a positively charged cation and a negatively charged anion. Terms Full Text Ions and Ionic Bonds Some atoms are more stable when they gain or lose an electron (or possibly two) and form ions. This results in a full outermost electron shell and makes them energetically more stable. Now, because the number of electrons does not equal the number of protons, each ion has a net charge. Cations are positive ions that are formed by losing electrons (as the number of protons is now greater than the number of electrons). Negative ions are formed by gaining electrons and are called anions (wherein there are more electrons than protons in a molecule ).

Anions are designated by their elemental name being altered to end in "-ide". For example, the anion of chlorine is called chloride, and the anion of sulfur is called sulfide. This movement of electrons from one element to another is referred to as electron transfer. As illustrated, sodium (Na) only has one electron in its outer electron shell. It takes less energy for sodium to donate that one electron than it does to accept seven more electrons to fill the outer shell . When sodium loses an electron, it will have 11 protons, 11 neutrons, and only 10 electrons. This leaves it with an overall charge of +1 since there are now more protons than electrons. It is now referred to as a sodium ion. Chlorine (Cl) in its lowest energy state (called the ground state) has seven electrons in its outer shell. Again, it is more energy efficient for chlorine to gain one electron than to lose seven. Therefore, it tends to gain an electron to create an ion with 17 protons, 17 neutrons, and 18 electrons. This gives it a net charge of -1 since there are now more electrons than protons.

It is now referred to as a chloride ion. In this example, sodium will donate its one electron to empty its shell, and chlorine will accept that electron to fill its shell. Both ions now satisfy the octet rule and have complete outer shells. These transactions can normally only take place simultaneously; in order for a sodium atom to lose an electron, it must be in the presence of a suitable recipient like a chlorine atom.

Question: Atoms that have either gained or lost electrons are called what?
Answer: Ions