Periodic Table Trends

The periodic table is not organized randomly, it follows certain trends.

There are some trends we need to know.

Here is a youtube video that pretty much covers EVERY trends we need to know.

Below are the trends summarized in point form :D

1) Metallic properties

• From left to right across the table, the elements change from metal to non-metal
• From top to bottom down the table, elements become more metallic, or better metals

2) Atomic radius

• From left to right across a row, the radius of atom decreases because increase in number of protons brings the electrons closer to the nucleus
• From top to bottom down a group, the radius increases

3) Atomic size

• From left to right across a period, the size decreases
• From top to bottom down a group, the size increases

4) Reactivity

• For metal:
• From top to bottom down a group, the elements become more reactive
• in transitional metals, the middle part of the table is the least reactive and to the left or to the right become more reactive
• the most reactive metal is Francium
• For non-metal (excluding noble gas):
• From top to bottom down a group, the elements become less reactive

5) Ion charge

• Metals tend to have positive charges
• Non-metals tend to have negative charges
• the transitional metals have variable charge

6) Melting & boiling point

• elements in the centre of the table have the highest melting and boiling point
• Noble gases have the lowest M & B point
• from left to the right across the table, the M & B point increases until the middle of the table

7) Ionization energy

• this is the energy required to completely remove an electron from an atom
• From bottom to up, left to right cross the table, the energy increases
• All noble gases have high ionization energy
• Helium has the highest ionization energy while Francium has the lowest
• Note: this trend is opposite from atomic radius trend

8) Electronegativity

• Electronegativity is basically how much atoms want to gain electrons
• Note: this trend is the same as the trend for ionization energy
• Noble gases are excluded from the trend as they already have full shells (so they don't want to gain or loss electrons)