Chemistry Patterns

Periodic Table Patterns

The periodic table is FULL of patterns.

• If you know the patterns, you can use it to find information quickly about the elements

• The two patterns we are going to review are the periods and the group numbers

Let's start with the periods

• periods are the name for the rows that go across the table

• there are 7 rows on the periodic table

• the pattern is the elements in a period have the same number of energy levels

• as elements get bigger with more electrons, the elements need more space for their electrons.

See?

• Energy level 1 with hydrogen and helium have only 1 and 2 electrons

• Energy level 2 from Lithium to Neon have two energy levels and have even more electrons

• Energy leve3 from sodium to argon have 3 energy levels and still more electrons!

Multiple Choice

How many energy levels does Calcium have in period 4

• 1

• 2

• 3

• 4

Multiple Choice

How many energy levels does sodium (Na) have in period 3?

• 1

• 2

• 3

• 4

Multiple Choice

How many energy levels does Neon have in period 2?

• 1

• 2

• 3

• 4

Multiple Choice

How many energy levels does helium have in period 1?

• 1

• 2

• 3

• 4

Okay! So the period number tells us the number of energy levels and element has.

• the bigger the number of electrons, the more energy levels it needs

• so as you go down the periodic table, the elements have more energy levels

• the maximum number of energy levels is 7

Now let's talk groups

• groups go up and down on the periodic table

• there are 18 groups on the periodic table

• BUT only groups 1 and 2 and 13-18 follow any sort of pattern.

• the pattern is the group number can help you quickly figure out the number of valence electrons

• valence electrons are the electrons on LAST energy level

• valence electrons are the ones responsible for bonding- so VERY important!

The Group Pattern

The group numbers 1,2 13-18 can help to quickly tell how many valence electrons there are for the elements in the group

The Group Pattern

The bolded number at the top of the group tell the number of valence electrons the group has.

Group 1 has 1 valence electron

Group 2 has 2 valence electrons

The Group Pattern

The bolded number at the top of the group tell the number of valence electrons the group has.

Group 13 has 3 valence electrons

Group 14 has 4 valence electrons

(see the pattern yet?)

Group 15 has 5

Group 16 has 6

Group 17 has 7

Group 18 (mostly) has 8

*Helium in group 18 is an exception - it only has 2 electrons!

Multiple Choice

How many valence electrons do element in group 2 have?

• 1

• 2

• 12

Multiple Choice

How many valence electrons do element in group 14 have?

• 1

• 4

• 14

Multiple Choice

How many valence electrons do element in group 18 have?

• 1

• 8, except Helium only has 2

• 18

Now, you are ready to practice the patterns!

Go find the link to the Quizizz