GAC 023GENERAL SCIENCE

Refina Ayu Alifa

Tsamara Alifia

Alifia and AlifaION

BasicWhat is ion?

An ion is a charged atom or molecule. It is charged when the number of electrons isn’t equal with the number of protons in the atom or molecule

What is atom?

singe particle that cant be broken down by chemical reaction.

What is molecule?

atoms join together to form molecule, only

non metals can bond together to form

molecules in a chemical bond.

How did it become an ion?

Metal atoms and non-metal atoms go in opposite directions when they ionize:

Metal atoms lose the electron, or electrons, in their highest energy level and become positively charged ions

Non-metal atoms gain an electron, or electrons, from another atom to become negatively charged ions

The process of an atom becoming an ion is called ionization.

Positive Ion (Cation)=> Occurs when an atom loses an

electron (negative charge)=> more protons than electrons.

Negative Ion (Anion)=> Occurs when an atom gains an electron (negative charge)=> more electrons than protons.

Example

HOW TO DETERMINE THE CHARGE?

The number of charges on an ion formed by a

metal is equal to the group number of the metal

The number of charges on an ion formed by a non-

metal is equal to the group number minus eight

Hydrogen forms H+ ions

EXAMPLE

Group 1 Group 2 Group

3 Group 4 Group5

Group 6 Group 7 Group 0

Example element Na Mg Al Co N O Cl He

Charge +1 +2 +3

Carbon & Silicon in group 4 usually form

covalent bond by sharing

electron.

-3 -2 -1

Don’t react with other

element to form

ion

Symbol OfIon

Na+ Mg2+ Al3+

Carbon & Silicon in group 4 usually form

covalent bond by sharing electron

N3- O2- Cl-

Don’t react with other

element to form

ion

Ionic Bond When metals react with non-metals:

Electrons are transferred from the metal atoms to the non-metal atoms, forming ions.

The resulting compound is called an ionic compound.

The metal atoms become positive ions and the non-metal atoms become negative ions.

There is a strong force of attraction between these oppositely charged ions, called an ionic bond

EXAMPLE

Na losing an electron & Cl gaining an electronThus the Na becomes Na+The Cl becomes Cl-

Covalent BondO A covalent bond is a strong bond between two

non-metal atoms. It consists of a shared pair of electrons.

O Covalent bonds are strong - a lot of energy is needed to break them

O Atoms may form multiple covalent bondsO There is a quick way to work out how many

covalent bonds an element will form. The number of covalent bonds is equal to:

8 - the group number

To see the number of Covalent bond

Hydrogen forms 1 covalent bondThe noble gases in group 0 don’t form any

Covalent bonds can be represented in

several different ways.

1. Straight lines and models

2. Double and triple bonds

3. Dot and cross diagram

Straight and line models

• Straight lines are the most common way to represent covalent bonds, with each line representing a shared pair of electrons.

Double and triple bonds

• Note that molecules can have a double covalent bond - meaning they have two

shared pairs of electrons - or a triple covalent bond - three shared pairs of

electrons.

• A double covalent bond is shown by a double line, and a triple bond by a triple line.

• A molecule of oxygen (O2) consists of two oxygen atoms held together by a double

bond, like this:

• A molecule of nitrogen (N2) has two nitrogen atoms held together by a triple bond,

like this:

Dot – and – cross diagram

• Dot-and-cross diagrams are another

way to represent covalent bonds.

The shared electron from one atom

is shown as a dot, while the shared

electron from the other atom is

shown as a cross.

• When drawing dot-and-cross

diagrams for covalent bonds, you

only need to show the electrons in

the highest occupied energy level, as

only these are involved.

References

http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/atomic/ionicrev4.

shtml

http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/atomic/covalentrev3.

shtml

http://www.chem4kids.com/files/atom_ions.html

http://www.qrg.northwestern.edu/projects/vss/

docs/propulsion/1-what-is-an-atom.html

http://www.microncorp.com/energaire/ions.html

1. What is an Ion?2. How did an ion became a cation?3. How did an ion became an anion?4. Mention 2 examples of Cation and Anion!5. What is an ionic Compound?6. What is a covalent bond?7. Mention three ways to present covalent

bonds!