Chemistry

There is nothing in our lives which does not have some chemical relavence

Everything we eat, feel and wear has been extensively researched by chemical means.

Through the recession, pharmaceutical job number have stayed static!

States of Matter

Law of conservation of energy

• Matter is neither created or distroyed in the course of a chemical reaction

The Atom

• The atom is the smallest particle which can not be broken down

Atomic particle properties

Periodic Table

Group I Elements

– They are soft metals which float in water– These elements react with water vigourously– They all have one electron in their outer shell

Group II Metal

– React with water– They have two electrons on their outer shell

The periodic table

• Shows the elements in order of increasing atomic number, periodic

• The vertical columns are called groups• The elements of each group have similar

properties

Group VII, Halogens

– The elements are very reactive non-metals– These elements have seven electrons on its outer

shell

Group O, the noble gases

• These elements have 8 electrons inits outer shell

• The elements are extremely unreactive

Valency

• Valency of an atom tells us the number of chemical bonds that an atom can form

The Octet Rule

• Atoms are at their most stable when they have full outer shell.• The exception is Helium which has a full outer shell.

(n=1, only 2 electrons)

– What is the Octet rule– Which group of metal are the most reactive?

Why?

The formation of Ions

• An ion is a positively or negatively charged atom.

• If an atom does not obey the Octet Rule it will strive to do so by loosing or gaining an electron(s).

• If an atom looses a electron, it becomes positively charged

• If an atom gains a electron, it becomes negatively charged

Ionic Bonding

• Atoms must become ions before they can engage in ionic bonding

• Ionic bonding is the attraction between positive and negative ions

Ionic bonding

• Sodium (Na) has one electron in its outer shell, therefore it will want to loose that electron

• Chlorine (Cl) has 7 electrons in its outer shell, therefore it will want to gain an electron to obey the octet rule.

Covalent Bonding• Covalent bonding: A bond in which atoms share

electrons

• This generally happens between atoms which have half empty shells

• For example hydrogen has one electron in its outer shell. It only needs one more to reach it maximum

• If two hydrogens share their electrons they will be more stable because they will effectively have two electrons in their outer shell.