1. Chemistry Year 9
Matter
Year 9 Science 2013

2. The History of Atomic Theory
All matter is made up of tiny particles called atoms
An atom is the smallest neutral particle that makes up matter.
Scientists and philosophers have guessed that all matter is made up of building blocks for a very long time. Discovery of the actual structure of the atom has only been in relatively recent times however.
The History of Atomic Theory
Year 9 Science 2013

3. All matter is made up of tiny particles called atoms
John Dalton (1766–1844) was a British chemist and physicist. In 1803 he announced his atomic theory.
My Theory States:
All Elements are made up off tiny particles called atoms.
Atoms of a given element are alike
Atoms of different elements are different
Chemical changes take place when atoms link up with or separate from one another
Atoms are not created or destroyed by chemical change
Year 9 Science 2013

4. All matter is made up of tiny particles called atoms
Sir Joseph John Thomson, who had discovered (1897) the electron, and came up with a model of the atom known as the plum-pudding model.
Year 9 Science 2013

5. All matter is made up of tiny particles called atoms
Ernest Rutherford was a New Zealand Scientist. In 1911 he announced his new atomic model based on what he observed from his famous ‘gold foil’ experiment.
Year 9 Science 2013

6. Ernest Rutherford’s Gold Foil experiment
All matter is made up of tiny particles called atoms
Ernest Rutherford’s Gold Foil experiment
“ It was the most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a cannon-ball at a piece of tissue and it came back and hit you.”
- Ernest Rutherford
Year 9 Science 2013

7. Atoms have a particular structure – protons, electrons and neutrons
Atoms have a central nucleus. The nucleus contains protons (p) and neutrons (n). Electrons (e) orbit the nucleus, arranged in shells or energy levels.
Electron -ve
Nucleus
Neutron N P N P N N P
Proton +ve P P P N N
This is known as the Bohr model.
Shell 1
Shell 2
Year 9 Science 2013

8. Atoms have a particular structure – protons, electrons and neutrons
Atoms are very small. Very special microscopes are required to see them. Many billions of atoms are required to produce this full stop.
Year 9 Science 2013

9. Atoms have equal number of protons and electrons
Protons are positively charged; electrons are negatively charged; neutrons have o electrical charge.
Atoms have no overall charge because the number of protons = number of electrons.
Summary
All matter is made up of atoms. Atoms consist of protons, neutrons and electrons.
The charges of protons and electrons are equal and opposite.
Year 9 Science 2013

10. Matter consisting of only one type of particle (atom) are elements
Pure substances made up of only one type of atom are called elements. There are 106 known elements and therefore 106 different types of atoms.
Elements can be grouped into metals and non-metals.
Most elements are found in their solid form on earth but some are also found as liquids and gases.
Element
Metal
Solid
Liquid
Non-Metal
Gas
Iron
Mercury
Sulfur
Bromine
Oxygen
Year 9 Science 2013

11. Atoms can exist in different arrangements
There are approximately 100 different elements but many millions of substances. Most matter around us is made up of combinations of elements.
If different elements are just jumbled up then they form a mixture.
If different elements have chemically reacted together and joined then they form a compound.
A molecule forms when atoms join together – either the same to form a molecule of an element or different to form a molecule of a compound.
Atoms of an element
Molecules of an element
Molecules of a compound
Mixture of elements and a compound
Year 9 Science 2013

12. Matter consisting of only one type of particle (atom) are elements
Most elements are metals. They are mostly all solids and shiny that can be bent into many shapes. They can conduct electricity and heat.
Iron
Gold
Copper
Sodium
Tin
Silver
Magnesium
Year 9 Science 2013

13. Matter consisting of only one type of particle (atom) are elements
Non-metal elements are not shiny and can’t be bent. They usually cannot conduct electricity.
Carbon
Sulfur
Oxygen
Neon
Phosphorus
Year 9 Science 2013

14. Each different type of element has a different number of protons in its atoms
All Boron atoms have 5 protons in their nucleus.
All Carbon atoms have 6 protons in their nucleus.
Year 9 Science 2013

15. Each element is named and has a specific symbol.
Elements consist of only one type of atom.
Each element can be represented by a chemical symbol.
Year 9 Science 2013

16. Understand there is a correct way of writing element symbols.
>Most symbols are one or two letters, formed from the name of the element e.g. Hydrogen H, or Helium He.
>The first letter of the symbol is always a capital letter. Any other letters are lower case e.g. Helium is He not HE
>If the symbols are not based on a elements English name then it is most likely to be based on it’s Latin name, the original language of Science.
Year 9 Science 2013

17. Understand that elements are arranged on the periodic table according to their atomic number.
Each element has an atomic number which tells us how many protons are contained inside each atoms nucleus. This number of protons is matched by an equal number of electrons which move around the nucleus.
The periodic table starts with Hydrogen (H) Atomic number 1 and ends with elements that have over 100 protons such as Copernicium (Cn) Atomic number 112.

18. Year 9 Science 2013

19. Understand the more protons an atom has the further down
the table it is.
Year 9 Science 2013

20. Learn that Groups of elements on the periodic table have common physical and chemical properties
Elements that are in the same group show similar types of chemical and physical properties. Their atoms chemically react the same way because their electrons in the outside shell in the atoms are arranged the same way.
Group 1 Metals
The elements in a group also have similar physical properties because of the way the atoms join together and are arranged.
Group 17 Non-Metals
Year 9 Science 2013

21. Groups are numbered vertical columns and periods are horizontal rows
The columns (downwards) of a periodic table are called groups.
The rows (across) of a periodic table are called periods.
Elements in the same group all have the same number of electrons in their outer (or valence) shells.
Elements in the same period all have the same number of shells of electrons in their atoms
Year 9 Science 2013

22. Metals are placed on the left hand side and non-metals are placed on the right hand side of the periodic table
Elements can be classified as metals or non-metals. A few elements are called semi-metals or metaloids (e.g. boron and silicon), because they show some, but not all, of the properties of metals.

23. The groups of metals and non-metals have specific defining physical properties
>Lustre (shiny)
>good conductor
>High density
>High melting point
>Malleable (can shape into sheets)
>Ductile (can shape into wires)
Semi-Metals
>Solids
>Can be shiny or dull
>Ductile and malleable
>Conduct heat and energy better than Non Metals but not as good as metals
Non-Metals
>No lustre
>Poor conductor
>Brittle >Not ductile >Low density >Low melting point 23

24. Matter exists in different states – solid, liquid and gases
Gases, liquids and solids can be made up of atoms, molecules, and/or ions, but the behaviours of these particles differ in the three states.
Solids remain in a fixed shape – the particles vibrate but remain tightly bonded to each other. Liquids take the shape of the container – the particles can move past each other but are still bonded. Gases fill any container they are in – the particles move fast and are not bonded to each other
Year 9 Science 2013

25. Matter can change from one state to another
condensation
Gas
evaporating
sublimation
deposition
Liquid
Freezing
Solid
If energy is absorbed or released the particles which make up the matter can change state. A change of state is a physical reaction and it is reversible.
Melting
Year 9 Science 2013

26. Characteristics of Gases, Liquids and Solids
Particles are arranged and move differently in solids, liquids and gases
Characteristics of Gases, Liquids and Solids
gas
liquid
solid
assumes the shape and volume of its container
particles can move past one another
assumes the shape of the part of the container which it occupies particles can move/slide past one another
retains a fixed volume and shape
rigid - particles locked into place
compressible
lots of free space between particles
not easily compressible
little free space between particles
flows easily
particles can move/slide past one another
does not flow easily
rigid - particles cannot move/slide past one another
Year 9 Science 2013
Year 9 Science 2013 26 26 SJ
Gaze

27. Particles are arranged and move differently in solids, liquids and gases
Solid particles are packed closely and only vibrate in a fixed position. Liquid particles are also packed closely but the particles move around more. Gas particles have a lot of space between them and move around quickly.
Gas
Liquid
Solid
Year 9 Science 2012
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28. Particles are arranged and move differently in solids, liquids and gases
The movement of particles in any state is determined by three factors: How strong the bonds are between the particles, how much energy (kinetic) the particles contain and the mass of the particles.
Particles move faster when: they have less mass, have weaker bonds between particles and have more energy.
Particles move slower when: they have more mass, have stronger bonds between particles and have less energy.
Year 9 Science 2013

29. The particles of different states have different kinetic energy levels
Kinetic energy causes particles to move. The more kinetic energy a particle has the faster it moves. Kinetic energy can be added to a particle by adding heat energy (and heats up). The heat energy is then transformed into the kinetic energy.
Kinetic energy can also be lost from a particle, which slows it down, when it changes back into heat energy and is lost (and cools).
Year 9 Science 2013