Datasets:

vasugoel

/

K-12Corpus

like 2

The concept of a magnetic field around a current carrying wire is explored and a simple method to determine the direction of the magnetic field is explained

Faraday's law Faraday's law relates the emf produced to the magnetic flux around a loop of conductor

The concept of electromagnetic induction is introduced and some simple calculations using Faraday's law are shown

Electromagnetism describes the interaction between charges, currents and the electric and magnetic fields to which they give rise

An electric current creates a magnetic field and a changing magnetic field will create a flow of charge

This has resulted in the invention of many devices which are useful to humans, for example cellular telephones, microwave ovens, radios, televisions and many more.

The study of electrical circuits is essential to understand the technology that uses electricity in the real-world

We depend on electricity and electrical appliances to make many things possible in our daily lives

This becomes very clear when there is a power failure and we can't use the kettle to boil water for tea or coffee, can't use the stove or oven to cook dinner, can't charge our cellphone batteries, watch TV, or use electric lights.Units and unit conversions - Physical Sciences, Grade 10, Science skillsEquations - Mathematics, Grade 10, Equations and inequalitiesGraphs - Mathematics, Grade 10, Functions and graphs

When a chemical reaction occurs, bonds in the reactants break, while new bonds form in the product

Hydrogen reacts with oxygen to form water, according to the following equation:In this reaction, the bond between the two hydrogen atoms in the molecule will break, as will the bond between the oxygen atoms in the molecule

New bonds will form between the two hydrogen atoms and the single oxygen atom in the water molecule that is formed as the product.For bonds to break, energy must be absorbed

The energy that is needed to break a bond is called the bond energy or bond dissociation energy

Bond energies are measured in units of .Bond energy Bond energy is a measure of bond strength in a chemical bond

It is the amount of energy (in ) that is needed to break the chemical bond between two atoms

Remember when we discussed bonding (chapter 3) we used the following energy diagram:We can use this diagram to understand why bond breaking requires energy and bond making releases energy

When a bond breaks, the atoms move apart and the distance between them increases (i.e

the atom moves to the right on the -axis or from point X to point A)

Looking at the diagram we see that when this happens, the energy increases (i.e

the energy at point A is greater than the energy at point X)

So when a bond breaks energy is needed.When a bond forms the atoms move closer together and the distance between them decreases (i.e

the atom moves to the left on the -axis or from point A to point X)

Looking at the diagram we see that when this happens, the energy decreases (i.e

the energy at point X is less than the energy at point A)

So when a bond forms energy is released.Looking at the example of hydrogen reacting with oxygen to form water:We see that energy is needed to break the bonds in the hydrogen molecule and to break the bonds in the oxygen molecule)

And we also see that energy is released when hydrogen and oxygen bond to form water)

When we look at the entire reaction and consider both bond breaking and bond forming we need to look at the enthalpy of the system.Enthalpy Enthalpy is a measure of the total energy of a chemical system for a given pressure, and is given the symbol H

A chemical system is a closed system that contains only the reactants and products involved in the reaction.As we learn about exothermic and endothermic reactions we will see more on the concept of enthalpy.

Up to now you have looked at reactions as starting with the reactants and going to the products

For acids and bases we also need to consider what happens if we swop the reactants and the products around

And that when (the base) gains a proton it forms (the acid)

In your own words explain what is meant by the term conjugate acid-base pair

A conjugate acid-base pair is a reactant and product pair that is transformed into each other through the loss or gain of a proton

So for example an acid loses a proton to form a base

The acid and the resulting base are said to be a conjugate acid-base pair

This chapter looks at the lithosphere and explores mining in more detail

Mining is very important in South Africa as a large part of the economy depends on gold, diamond and coal mining

This chapter looks at the history of mankind, what the lithosphere is, what is in the lithosphere and then goes on to look at mining

The general techniques used across all types of mining are looked at and then gold mining is explored in greater detail

Learners can do the mining section as a project (either in groups or individually) that they then present to the class

If learners do a project ensure that each mineral listed in CAPs (iron, phosphate, coal, diamond, copper, platinum, zinc, chrome, asbestos, manganese and gold) is covered by at least one learner in the class.This topic provides a great opportunity to look at social justice and economic concerns

The various class discussions and debates provided give learners the chance to think about some critical issues in South Africa.In Grade 10 we studied the elements

We learnt about the different elements and the compounds that could be formed from those elements

Where did mankind find them and how has he used them?This chapter will explore the part of the Earth known as the lithosphere

We will find out what the lithosphere is and how the elements are distributed within it.

All the objects that we see in the world around us, are made of matter

Matter makes up the air we breathe, the ground we walk on, the food we eat and the animals and plants that live around us

Even our own human bodies are made of matter!Different objects can be made of different types of materials (the matter from which objects are made)

For example, a cupboard (an object) is made of wood, nails, hinges and knobs (the materials)

The properties of the materials will affect the properties of the object

In the example of the cupboard, the strength of the wood and metals make the cupboard strong and durable

Materials that are malleable can be easily formed into different shapes (eg clay, dough)

Ductile materials are able to be formed into long wires (eg copper)

The boiling and melting points of substances tells us the temperature at which the substance will boil or melt

This helps us to classify substances as solids, liquids or gases at a specific temperature

The diagram below shows one way in which matter can be classified (grouped) according to its different properties

As you read further in this chapter, you will see that there are also other ways of classifying materials, for example according to whether or not they are good electrical conductors.

In this chapter we will explore the states of matter and then look at the kinetic molecular theory

We will also examine how the kinetic theory of matter helps explain boiling and melting points as well as other properties of matter

Diffusion can be seen as a spreading out of particles resulting in an even distribution of the particles

You can see diffusion when you place a drop of food colouring in water

If matter were not made of particles that are constantly moving then we would only see a clump of colour when we put the food colouring in water, as there would be nothing that could move about and mix in with the water

In 1828 Robert Brown observed that pollen grains suspended in water moved about in a rapid, irregular motion

Brownian motion can also be seen as the random to and fro movement of particles

Matter exists in one of three states, namely solid, liquid and gas

A liquid takes on the shape of the container that it is in

Matter can change between these states by either adding heat or removing heat

As we heat an object (eg water) it goes from a solid to a liquid to a gas

Evaporation from a liquid's surface can happen at a wide range of temperatures

If more energy is added then bubbles of gas appear inside the liquid and this is known as boiling

Sublimation is the process of going from a solid to a gas

Deposition is the process of going from a gas to a solid

If we know the melting and boiling point of a substance then we can say what state (solid, liquid or gas) it will be in at any temperature

A heating curve of a substance gives the changes in temperature as we move from a solid to a liquid to a gas

A cooling curve gives the changes in temperature as we move from gas to liquid to solid

An important observation is that as a substance melts or boils, the temperature remains constant until the substance has changed state

This is because all the heat energy goes into breaking or forming the bonds between the molecules

The following diagrams give examples of what heating and cooling curves look like:

We have now looked at many examples of the types of matter and materials that exist around us and we have investigated some of the ways that materials are classified

In order to understand this, we need to take a closer look at the building blocks of matter — the atom

Atoms are the basis of all the structures and organisms in the universe

The planets, sun, grass, trees, air we breathe and people are all made up of different combinations of atoms.Video: VPrkk

The periodic table of the elements is a method of showing the chemical elements in a table with the elements arranged in order of increasing atomic number

Most of the work that was done to arrive at the periodic table that we know can be attributed to a Russian chemist named Dmitri Mendeleev

Mendeleev designed the table in 1869 in such a way that recurring (periodic) trends or patterns in the properties of the elements could be shown

Using the trends he observed, he left gaps for those elements that he thought were “missing”

He also predicted the properties that he thought the missing elements would have when they were discovered

Many of these elements were indeed discovered and Mendeleev's predictions were proved to be correct

To show the recurring properties that he had observed, Mendeleev began new rows in his table so that elements with similar properties were in the same vertical columns, called groups

The full periodic table is reproduced at the front of this book

These are the energies needed to remove the second, third, or fourth electron respectively

If you look at a periodic table, you will see the groups numbered at the top of each column

The groups are numbered from left to right starting with 1 and ending with 18

This is the convention that we will use in this book

On some periodic tables you may see that the groups are numbered from left to right as follows: 1, 2, then an open space which contains the transition elements, followed by groups 3 to 8

A period is a horizontal row in the periodic table of the elements

The periods are labelled from top to bottom, starting with 1 and ending with 7

For each element on the periodic table we can give its period number and its group number

We can also determine the electronic structure of an element from its position on the periodic table

In Chapter 4 you worked out the electronic configuration of various elements