groups- The vertical columns labeled from 0 to VII

periods- The horizontal rows labeled from 0 to 7

Valency electrons- The most outer shell electrons they are important because they dictate how an element behaves

unreactive- The atoms of Group 0 have a very stable arrangement of electrons in the outer shell (8), this makes them unreactive

nucleon number- the total number of particles in the nucleus (Proton+Neutron) <top right of the symbol>

Proton number- number of proton <bottom right of the symbol>

Groups with special name- Group I; Alkali Metal

Group II; The Alkaline Earth Metal

Group VII; The Halogen

Group 0; The Noble Gas

Period numbers- tell you the number of electron shells in the atom

- Are Poisonous

- Form Diatomic Molecules

- As you go down the periodic table the gas:

> color gets deeper

> density increases

> boiling points increase

- The reactivity of halogens are HIGH. They react with metals to form compounds called halides.

Yet, the reactivity decreases as you go down the column.

- The way it reacts is similar because all halogens have seven valency electrons.

(Atoms with the same valency electron react in a similar fashion.)

The reason on why it reacts harshly is because the halogens actually have seven valency electrons.

The halogens try to strive to react with other atoms to become a stable compound.

argon, krypton, and zenon.

They are all :

nonmetals

colourless gases they occur naturally in air

monatomic - exist as a single atom

unreactive they don't normally react with anything.

They are unreactive because :

they react to gain a stable outer shell of electrons but because noble gases already have a stable outer shell of electrons.

Since the noble gases are unreactive or inert thats what makes them safe to use.

HELIUM

is used to fill balloons and airships and it will not catch on fire.

ARGON

is used to provide an inert atmosphere.

NEON

Is used in advertising signs, it glows red the colour can be changed by mixing it with other noble gases.

KRYPTON

is used in lasers

XENON

gives light like a bright light daylight.

Some of them are violently reactive (except for the first three)

Alkali metals are not typical metals

Good conductors of heat and electricity

softer and lighter than typical metals (lower density)

float on water

low boiling and melting points compared to typical metals

The alkali metals are highly reactive with water

All the alkali metals react similarly because they all have the same number of

valency electrons (electrons in the outer shell)

Most reactive of all metals

They only have one valency electron to get rid of, so they are desperate to react with other elements and compounds

The Alkali metals form ionic compounds (have a charge of 1+) since they lose one of their electrons.