Atomic structure

All atoms have equal numbers of protons and electrons

Number of protons=atomic Number

Number if electrons= atomic number

Number of neutrons=mass number-atomic number

1st shell can hold up to 2 electrons

2nd shell can hold up to 8 electrons

3rd shell can hold up to 8 electrons

4th shell can hold up to 18 electrons

The period number (periodic table) tells you how many shells it has

The group number (periodic table) tells you the number of electrons in the outer shell

Element: a substance made up of only one type of atom

When elements react together, the atoms try and become more stable(happy) by having full outer electron shells

All of the group 1 alkali metals:

-must be stored in oil to stop them from reacting with the air

-they react with water

-all dense

-all fizz and make a gas

-all soft

The are all the in the same group and all behave in a similar way

Metal atoms all lose electrons to form positive ions

None metal atoms gain electrons to make negative ions