Coh3 chemical name

CHEMISTRY 

 Atom 

An atom is the smallest  stable unit of matter 

Element 

An element is a pure substance made of only one type of atom.

There are about 120 elements , so 120 different atoms exist.

In the periodic table the elements are organized in rows.

The vertical columns are called groups

The horizontal rows are called periods. 

Li, Na and k are in the same group 

N , O , F are in the same period. 

If the elements are in the same group they have the same number of electrons in the outer shell.

This elements in their same groups can have similar chemical and physical  properties. 

Some groups have specific names :

Group 1 elements : are named ALKALI 

Group 2 elements : ALKALI EARTH METALS

Group 7 elements : HALOGEN 

Group 0 elements : NOBLE GASES 

Group 1 - ALKALI metals 

Lithium - atomic number 3 :(2,1)

Sodium- atomic number 11 : (2,8,1)

Potassium - atomic number 19 : (2,8,8,1)

Rubidium 

Caesium 

 METALS AND NON-METALS 

NON-METALS 

Fluorine : sodium fluoride 

chlorine : pool , cleaning products 

bromine : some medicine , fire resistant plastic 

Iodine : test for starch iodoform , added to table salt.

Astatine : highly radioactive and unstable

TRANSITION METALS 

NORMAL PROPERTIES OF TRANSITION METALS 

Shared with group 1

 Grey in colour (usually)

Shiny 

May be essential minerals diet

Good conductors heat + electricity 

Not Shared with group 1

High melting points 

Harder + stronger 

Less reactive

Catalysts - elements or compounds

elements in group 7 

First 5 elements: 

Fluorine

Chlorine 

Bromine 

Iodine 

Astatine 

Fluorine atomic number 9 :  2,7 

Chlorine atomic number 17 : 2,8,7 

STRUCTURE OF AN ATOM  

Mass (amu)

Charge 

Proton 

1

 +

Neutron 

1

 o

Electron 

1/2000 or 0 

 -

Electronic  structure 

The electrons are arranged in orbits called shells 

First shell holds up to 2. 

Second shell holds up to 8. 

Third shell can hold up to 8 .

Then you continue up to the fourth shell.