1. Chemistry

2. Atoms, elements and compounds
All substances are made up of atoms.
An atom is the smallest particle of an element that has all the characteristics of that element, and that can exist on its own.
Atoms of the same element are identical
Atoms of one element differ from atoms of another element (an atom of gold is different from an atom of silver). All atoms of the same kind form and element of that kind of atom.
The element carbon contains only carbon atoms, thus diamonds and graphite contain the same atoms (allotropes of carbon, merely joined together differently)
Atoms are so small that scientists need to study the properties of the substance so that they can develop a model of the structure of atoms.

3. Copy these definitions into your books page 1: Elements
An element is a substance that cannot be broken down into a simpler form.
Each element is made up of one kind of atom, for example copper wire consists of only one kind of atom or the gas neon, contains only neon atoms
Compound
Two or more different types of atoms which are chemically joined make up a compound, for example carbon dioxide (CO2)
Mixture
A mixture is two or more substances that are mixed together but can be physically separated, for example sea water is a mixture of salt and water

4. Structure of the atom The nucleus
The atom is mostly empty space. The nucleus is found in the center of the atom. Surrounding the nucleus are electrons. The amount of electrons differs for different elements
The nucleus
The nucleus consists out of protons and electrons. Protons are particles with a positive charge while neutrons have no charge at all. Neutrons are slightly heavier than the protons.
Electrons: Surrounding the nucleus and moving around in the outer section of the atom are electron, 1836 electrons would have the mass of one proton. Electrons are negatively charged.

5. The Periodic table
Scientists describe oxygen carbon or helium as elements. An element is made up of only one substance. There are 92 natural elements. All these elements are listed in the periodic table.
Each element has its own symbol, which is a short way of writing that element. Most of the time the symbol is the first letter or two letters of the symbols name, for example Hydrogen is H. the symbol always begins with a capital letter.
NAME
Symbols and derivitive
Sodium: Na from the Latin word Natrium
Lead: Pb from the Latin wor Plumbum
Mercury: Hg from the Latin word Hydrargyrum
Gold: Au from the Greek word Aurum
Some elements such as gold silver and tin have been known for thousands of years. These elements have Greek or Latin names:

6. The Periodic table
Vertical columns are called groups. Elements in the same group, have the same number of electrons in their outer electron shell. Groups are numbered Group I to VII and Group 0
Elements of the same group have very similar properties because they have the same number of electrons in their outer shells
Horizontal rows of elements are called periods. Elements in the same period have the same number of shells of electrons

7. Structure of the atom The nucleus
The atom is mostly empty space. The nucleus is found in the center of the atom. Surrounding the nucleus are electrons. The amount of electrons differs for different elements
The nucleus
The nucleus consists out of protons and electrons. Protons are particles with a positive charge while neutrons have no charge at all. Neutrons are slightly heavier than the protons. The nucleus is the heaviest part of the atom
Electrons: Surrounding the nucleus and moving around in the outer section of the atom are electron, 1836 electrons would have the mass of one proton. Electrons are negatively charged.

8. The structure of the atom continued
The overall charge on an atom is neutral.
The positive charge of the nucleus balances out the negative charge of the electrons.
Thus if there are 5 electrons each with a charge of –1, the nucleus of the atom will have 5 positively charged protons to balance it out.

9. Electron arrangement
According to something called quantum theory, an electron can be found anywhere around the nucleus
Using advanced math, scientists are able to approximate, or guess, that electrons are in general areas.
These general areas are called the shells. Each Shell can only hold a limited number of electrons.
The way in which electrons occupy the orbits is called electron configuration.

10. Highly simplified orbital structure of the atom
1st shell 2 electrons
3rd Shell 8 electrons
2nd shell 8 electrons

11. Bohr Diagram 1st shell 2 electrons 2nd shell 8 electrons
3rd Shell 8 electrons
2nd shell 8 electrons
The arrangement of electrons in a shell was first proposed by a Danish scientist Niels Bohr. This diagram is called a Bohr Diagram. Static representation f electron configuration.

12. A volume of space where there is a 95% chance of finding an electron is an orbital, these orbital differ in shape. This is for interest only.

13. Compound and molecule
A chemical compound is a chemical substance consisting of two or more different chemically bonded elements, with a fixed ratio determining the composition.
A molecule is generally an aggregate of at least two atoms in a definite arrangement held together.
A chemical compound can have one or many molecules
The chemical compound 4H2SO4 contains 4 molecules of sulphuric acid. A compound could be described as a collective word used to describe a number of molecules.
The compound H2SO4 contains 1 molecule.

14. Formulae
A molecule is where two or more atoms join together to form a compound
If the atoms are the same for example O2 or N2 they are called diatomic molecules
The symbol for a compound is called its formula.
A formulae for a compound is made up of the symbols of its constituent parts as well as numbers representing how many atoms of each element are present
For example: the formula for 1 molecule of sulphuric acid is H2SO4
H2SO represents 1 molecule of sulfuric acid containing 2 atoms of hydrogen, one atom of sulphur and 4 atoms of oxygen.

15. Symbols and formulae
All the elements of the periodic table have symbols. Ca is the symbol for Calcium, H for Hydrogen and O for Oxygen.
The symbol represents one atom of that element
If you want to represent 2 atoms of that element you write a large no 2 in front of that element
2 Cu means that you have two atoms of copper
When a symbol is followed by a number for example H2 it means that there are two atoms of Hydrogen for the one molecule of hydrogen. H2
This 2 represents 2 atoms of hydrogen
No number means 1 molecule

16. H O
Element
1 Molecule of H2O
If you add these together you will have a compound containing two molecules of water. H O
Element
1 Molecule of H2O

17. H O 2 H O OR
H2O H2O = H2O
The compound water containing one molecule of water plus the compound water containing one molecule of water join to form the compound water containing two molecules of water.

18. H2SO4 1 atom of sulphur 2 atoms of hydrogen
1 molecule of sulfuric acid
4 atoms of oxygen
2 atoms of hydrogen

19. Ca(OH)2 This is one molecule of calcium hydroxide
There is only one Calcium in this compound
The 2 after the brackets means that you have to multiply all the elements in the bracket by 2, thus there are 2 oxygen and 2 hydrogen atoms

20. 2Ca(OH)2 This represents 2 molecules of calcium hydroxide
There are now 4 oxygen and 4 hydrogen atoms
There are 2 calcium in this compound

21. Bohr in Motion Lithium 3 electrons Protons Neutrons Electrons
The electron configuration for an element shows the exact electron arrangement for that element: for lithium it would be Li (2, 1).
Electron pairs spin in opposite directions within the orbital

22. Li 7 3
Atomic number
Mass number .

23. Li 7 3 Mass numbers and atomic numbers Mass number Atomic number
In chemistry and physics, The mass number is the number of protons and neutrons in the nucleus of an atom. Electrons weigh almost nothing, as a result the the protons and neutrons make up the mass of the atom.
The atomic number (Z) (also known as the proton number) is the number of protons found in the nucleus of an atom. In an atom of neutral charge, the number of electrons equals the atomic number. Li 7 3
Atomic number
Mass number

24. Li 7 3 Protons + Neutrons Protons
Atomic number
Mass number
Protons
= no of electrons
Mass no – atomic no = the number of neutrons
In a neutral atom the total number of protons is equal to the total number of electrons

25. More on protons
Every atom has a unique number of protons. Thus no two atoms have the same number of protons.
All atoms with 1 proton and thus 1 electron will always be Hydrogen. All atoms with 6 protons will always be Carbon
Proton numbers are the elements fingerprints

26. Electron configuration
Oxygen 8 electrons: O (2, 6)
Sodium 11 Na (2, 8, 1)
Phosphorous 15 P (2, 8, 5)
Argon 18 Ar (2, 8, 8)
How do we draw Bohr diagrams for them?
1st shell 2 electrons
2nd shell 8 electrons
3rd Shell 8 electrons

27. A neutron walked into a bar and asked how much for a drink
The bartender replied, "for you, no charge."

28. P N

29. A chemical compound is a combination of two or more elements
Why do compound form??? Na
A full outer shell makes an atom more stable.
By reacting with each other atoms obtain full outer shells and become more stable.

30. Noble gases do not usually form compound?
Why??
Neon 10 electrons
Ne (2.8) Ne

31. All the noble gasses have full outer electron shells and are thus stable and very uncreative (Group 8 on your periodic table)
All other elements have incomplete outer shells and will react to try and fill these shells

32. Most elements form compounds Sodium + Chlorine: Pass the Salt, Please
Sodium is a silver-coloured metal which is soft enough to cut with a knife.  It is an extremely reactive metal.  Pure sodium metal reacts violently (and sometimes explosively) with water, producing sodium hydroxide, hydrogen gas, and heat:
Chlorine is a poisonous, yellow-green gas, with a very sharp odor, and was used in gas warfare during World War I.
Sodium and chlorine react with each other, however, to produce a substance that is familiar to almost everyone in the world:  sodium chloride, or table salt:
Sodium  +  chlorine  ——>  NaCl

33. + means react with Sodium + chlorine NaCl
The arrow means to form
So the sentence Sodium  +  chlorine   NaCl
Means that sodium reacts with chlorine to form sodium chloride

34. The reaction is extremely exothermic, producing a bright yellow light and a great deal of heat energy.
How do you do it
A bottle is filled with chlorine gas.  A coating of sand on the bottom of the bottle absorbs some of the heat energy produced during the reaction, and prevents it from breaking.  A small piece of freshly-cut metallic sodium is placed in the flask, and then a small amount of water is added, which reacts with the sodium and causes it to become hot.  The hot sodium then reacts with the chlorine, producing a bright yellow light, a great deal of heat energy, and fumes of sodium chloride, which deposits on the walls of the bottle.

35. Na Cl
Sodium 11 Na (2, 8, 1)
Chloride 17 Cl(2,8,7)

36. Na 7 empty spaces: Cl 1 empty space
7 + 1 = 8 a full outer shell and a more stable element
Sodium loses and electron and Chlorine gains 1

37. Gaining and losing electrons
Some atoms obtain full shells by gaining electrons and some by losing electrons when they react with another element
When and element gains or loses and electron we refer to that element as an ion with either a positive charge or a negative charge.
Thus an ion is a charged particle. It is charged because it contains unequal numbers of protons and electons
FOR EXAMPLE
Sodium has one electron in its outermost (valence) shell, while chlorine has seven electrons in its valence shell.  When a sodium atom transfers an electron to a chlorine atom, forming a sodium ion (Na+) and a chloride ion (Cl-), both ions have complete valence shells, and are energetically more stable. 

38. Element Symbol P E Gains or losses Net charge Electrons - protons
Electron configuration
Sodium atom Na
11p
11e
No charge
Na (2,8,1)
Chlorine atom Cl
17p
17e
Cl (2,8,7)
Sodium ion
Na+1
10e 1
+ 1
Na (2,8)
Chlorine ion
Cl-1
18e
- 1
Cl (2,8,8)

39. Li O Li

40. O H H

41. Reaction rules
Atoms react to form full outer shells so that they become stable. Noble gases have full outer shells and are thus uncreative.
Atoms with less than 4 electrons in their outer shell lose electrons and form positive ions (+). This occurs with metals.
Atoms with more than 4 electrons in their outer shells gain electrons and form negative ions (-). This occurs with non-metals
Ionic bonding (Electrovalent bonding), Electrons are transferred and ions are formed. Always between a metal and a non-metal. Write the metal first and change the ending of the non metal to –ide eg sodium plus chlorine = sodium chloride

42. I II III IV V VI VII Na+ Ca2+ AL3+ N3- O2- F1- Loses 1e Loses 2e
Valence electrons: the number of electrons available to bond: I II
III IV V VI
VII
Loses 1e
Loses 2e
Loses 3e
Gains or loses 4e
Rarely gains
Gains 3e
Gains 2e
Gains 1e
Na+
Ca2+
AL3+
N3-
O2-
F1-

43. Covalent bonding: electrons are shared between atoms
Question 3 page 25
OH -
One Oxygen- 6 valence electrons
One hydrogen- 1 valence electron
SO4-2
One Sulphur – 6 valence shell electrons each
Four Oxygen – 6 valence shell electrons each
CO3-2
One Carbon: 4 valence electrons each
Three Oxygen: 6 valence electrons each

44. Metal ion Flame colour Li + Scarlet red Na + Orange-yellow K +
Group I elements page 27a
Compounds from the same group have similar properties.
For example group one are all soluble solids that dissolve easily in water.
They are also white unless negative ions give out a different colour. We can use colour to determine if there is a metal ion present in a compound. The compound will burn a different colour, depending on what ion is present
Metal ion
Flame colour
Li +
Scarlet red
Na +
Orange-yellow
K +
Lilac pink
Rb +
Red

45. Compound Flame colour Metal Ion A B C D Experiment page 27a
Determine what ion your compound contains.
Compound
Flame colour
Metal Ion A B C D

46. Naming a compound pg 81
Rules
The name of the ions are put together with the positive ion stated first
Hydrogen and the metals form positive ions which have the same name as the atoms, for example Lithium ion
Non metals form negative ions and their name ends in -ide for example sulphide ion.
In a compound where there are groups of atoms, the name of the compound ends in –ate for example Sodium sulphate Na2So4. Anything ending in OH has the suffix -hydroxide
Group IV and V elements do not usually form ions because their atoms would have to gain or lose too many electrons which take too much energy.
Noble gases do not form ions as their outer shells are full.

47. The ability of atoms to combine is called the valency page 29:
Cl- valency of one and can form one bond, it is a group 7 element, it has 7 valence shell electrons and needs one more to fill it outer shell
O - Oxygen has a valency of 2 it can form two bonds, it is a group 6 element, has six valence shell electrons and need two more to fill its outer shell
-N- Nitrogen has a valency of 3 and can form 3 bonds, it is a group 5 element, it has 5 valence shell electrons and needs 3 more to fill its outer shell.
Carbon four - C -

49. Compound ions are ions that form from groups of atoms that are joined together to form a compound
MEMORISE THES IONIC COMPOUNDS
NH4 + Ammonium ion OH - Hydroxide ion
NO3 - Nitrate ion SO4 2- Sulphate ion
HCO3 2- Hydrogen carbonate ion CO3 2- Carbonate ion

50. Interest only
Luciferin

51. Diatomic molecules.
Al the elements in group seven (VII) as well as oxygen and nitrogen exist only as molecules.
Fluorine F2
Chlorine Cl2
Bromine Br2
Iodine I2
At…….
Oxygen O2
Nitrogen N2
In the pure form, these atoms join together to form diatomic molecules. If however there are atoms of different kind they will bond with these. When using them in an equation you must write them as diatomic molecules.

52. Equations for chemical reactions:
When hydrogen is combined with oxygen it produces water
The hydrogen and oxygen are called reactants and the water or H2O is called the product:
This reaction can be shown using a diagram

53. This same reaction can be shown using symbols
H2 + O H2O
REACTANTS PRODUCTS
2H2 + O2 2H2O
The number of hydrogen and oxygen atoms on the left is equal to that on the right. Atoms do not disappear they are simply rearranged.

56. Rules for balancing equations.
Once the number of different atoms on both side of the equation are the same, the equation is balanced. An unbalanced equation is not correct.
Rules for balancing equations.
Write the equation in words
Write the equation in symbols and formulae.
Check that the formulae are correct
Count the number and kind of each atom on the left and the right side of the equation. Balance the equation so that the they are equal.
NB when balancing an equation you may only place numbers in front of the element or formulae. Placing number behind the formulae or in-between symbols will change the chemical structure of that compound.

57. hydrogen + chlorine hydrogen chloride
magnesium + oxygen magnesium oxide
calcium + chlorine calcium chloride
Balancing equations online

58. The end