Groups in Periodic Table

What is a periodic table?

A list of elements arranged in order of increasing atomic number.

What are metals and non-metals?

Elements can be classified based on their properties, with metals typically being shiny, malleable, and forming bases, while non-metals form acids.

Define alkali metals.

Group 1 elements in the periodic table with properties like silvery appearance, low density, and reactivity with water to form metal hydroxide and hydrogen.

Define Halogens.

Group 7 elements in the periodic table, non-metals occurring as diatomic molecules, with trends of increasing color darkness and melting/boiling points down the group.

Define noble gases.

Group 8 elements in the periodic table, inert gases with full valence shells, unreactive due to their stable electron configuration.

What are Physical Properties of grp 1 metals?

1. Silvery/shiny when freshly cut

2. Soft (easily slice with a knife) – become softer as you move down the group

3. Low density – float on water

4. Conduct electricity

Chemical properties of group 1 metals.

• They react with water to give a metal hydroxide and hydrogen

• They become more reactive with increasing atomic number (as you go down the group)

Why is there a similarity in chemical properties within a group?

due to all members having the same number of electrons in the outer shell.

Li + H2O

2Li(s) + 2H_2O(l) → 2LiOH + H_2(g)

Na + H2O

2Na(s) + 2H_2O → SNaOH(aq) + H_2(g)

K + H2)

2K(s) + 2H_2O(l)  → 2KOH(aq) + H_2(g)

Trend of reactivities of halogens.

They become less reactive as you go down the group

Trends of physical property in group 7

• They become darker in color

• Their melting point/ boiling point increases (hence the gradual change in state at room temperature from gas to liquid to solid)

Chlorine + Potasssium Bromide

Why are group 8 elements unreactive?

They are very unreactive because they all have full valence shells and hence have a valency of 0.