4.5 Building blocks for understanding 4.5.1 The periodic table Spec ref. Summary of the specification content Learning outcomes What most candidates should be able to do Suggested timing (hours) Opportunities to develop scientific communication skills Opportunities to apply practical and enquiry skills Self/peer assessment Opportunities and resources Reference to past questions that indicate success 4.5.1.1 The elements in the periodic table are arranged in order of atomic (proton) number and so that elements with similar properties are in columns, known as groups. The table is called a periodic table because similar properties occur at regular intervals. Electrons occupy particular energy levels. Each electron in an atom is at a particular energy level (in a particular shell). The electrons in an atom occupy the lowest available energy levels Explain how the position of an element in the periodic table is related to the arrangement of electrons in its atoms and hence to its atomic number. Predict possible reactions and probable reactivity of elements from their positions in the periodic table. Show how scientific methods and theories have changed over time. to 4.1.2 Atomic structure. 1 Identify link between electron configuration and the structure of the periodic for elements 1 to 20. Identify anomalies. Discussion questions: Why isn't the periodic table a regular rectangular shape? In what ways are elements like letters of the alphabet? WS 1.2 Represent the electronic structure of the first 20 elements of the periodic table in the following forms: sodium 2,8,1 WS 1.2 Predict possible reactions and probable reactivity of elements Video clip: BBC Bitesize – Groups and periods in the periodic table YouTube: Teachit Science resource (19411) ‘Electron configuration’ YouTube: or (interactive) University of Nottingham –
4.5.1.2 The majority of elements are metals. Metals are to the left and towards the bottom of the periodic table. Non-metals are found towards the right and top of the periodic table. Elements that react by losing their outer electrons to form positive ions are metals. Elements that do not form positive ions are non-metals. The more reactive non-metals, such as the halogens, react with metals by gaining electrons to form negative ions. Explain the differences between metals and on the of their characteristic physical and chemical properties. Explain how the atomic structure of metals and relates to their position in the periodic table. Explain how the reactions of elements are related to the arrangement of electrons in atoms and hence to their atomic number. 0.5 WS 1.2 Describe metals and non-metals and explain the differences between them in terms of their characteristic physical and chemical properties (see 4.6.2 Structure and bonding and the sections about groups 1, 7 and 0 in this topic). YouTube: 4.5.1.3 The elements in Group 0 of the periodic table are called the noble gases. They are unreactive and do not Explain how properties of the elements in Group 0 depend on the outer shell of electrons of the atoms. 1 Extended writing: Describe the trends in properties in Group 0. WS 1.2 Predict properties from given trends down Group 0.
easily form molecules because their atoms have stable arrangements of electrons. The noble gases have eight electrons in their outer energy level, except for helium, which has only two electrons. The boiling points of the noble gases increase with increasing relative atomic mass (going down the group). Predict properties from given trends down the group. Explain how properties of the elements in Group 0 depend on the outer shell of electrons of the atoms. High demand: Explain the trends in Group 0. 4.5.1.4 The elements in 1 of the periodic table are as the alkali metals. They: •are soft metals with low density •react with non-metals, including chlorine and oxygen, to form colourless ionic compounds with water Explain how properties of the elements in 1 depend on the outer shell of electrons of the atoms. Predict properties from given trends down the group. 1 Discussion question: What makes an element reactive? Extended writing: Describe the trends in properties in Group 1. Explain how properties of the elements in Group 1 depend on the outer shell of electrons of the atoms. WS 1.2 Demo reactivity of Na, Li and K in water with universal indicator. Predict reactions for Rb, Cs and Fr.
more new substances, and often involve a detachable energy change. Chemical reactions can be represented by word equations or equations using symbols and formulae. In chemical equations, the states of matter are shown as (s), (l) and (g), with (aq) for aqueous solutions. 4.5.2.2 The law of conservation of mass states that no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants. This means that chemical reactions can be represented by WS 1.2 Pupils should understand the use of the multipliers in equations in normal script before a formula and in subscript within a formula. WS 1.2 Pupils should be able to explain any observed changes in mass in systems during a 3 Use the following quotes to relate to and discuss the law of conservation of mass: Nasir al-Din al-Tusi, Persian Muslim scholar said 'A body of matter cannot disappear. It only changes into a different form ...' Empedocles, 490–430 BC. philosopher 'nothing comes from nothing.' Model the law of conservation of mass using molecular model kits. Lego or Duplo bricks can be used to good effect. Teacher demonstration. The precipitation reaction: lead nitrate + potassium iodide clips: YouTube: YouTube: (burning iron wool experiment at 7 minutes in)
mass may decrease because products are released to the air as gases. Try balancing iron wool on a pair of scales (a makeshift one can be set up using a carefully balanced metre rule). Heat the iron wool strongly to observe the increase in mass of the oxide. 4.5.2.3 The relative atomic mass of an element compares the mass of atoms of the element with the 12C isotope. It is an average value for the isotopes of the element. The relative formula mass (Mr) of a compound is the sum of the relative atomic masses of the atoms Pupils are expected to use relative atomic masses in the calculations specified in the subject content. MS 1a, 3a Calculate the relative formula mass (Mr) of a compound from its formula, given the relative atomic masses. 1 Review the definition of relative atomic mass. Recall how to find the relative atomic mass from the periodic table. Define the relative molecular mass. Extended writing: instructions to another student how to calculate the relative formula mass.
and one mole of hydrogen gas. 4.5.2.6 (HT only) Many chemical reactions take place in solutions. The concentration of a solution can be measured in mass per given volume of solution, eg grams per dm3 (g/dm3). MS 1c, 3c Pupils should be able to: explain how the mass of a solute and the volume of a solution is related to the concentration of the solution calculate the mass of solute in a given volume of solution of known concentration in terms of mass per given volume of solution. 0.5 Explain the meaning of concentration and the unit grams per dm3 . Be able to convert cm3 into dm3 . Use the equation: to calculate the concentration of a solution. Rearrange the equation: to make mass the subject. Extended writing: Write instructions to another student on how to calculate the concentration, or how to rearrange the equation to calculate mass. Discuss the differences of the word ‘concentration’ and To demonstrate the idea of concentration pupils could make different concentrations of tea, coffee or a dark squash like blackcurrant. Pupils often confuse the concept of ‘concentration’ with ‘strength’. Video clip YouTube: