Element Number of valence Chemical family electrons name Si Ar

[Pages:21]RECAP

? Fill in the table below.

Element

Si

Number of valence electrons

4 ve-

Chemical family name

Carbon family

Li

1 ve-

Alkali metal

Ar

8 ve-

Inert/noble gas

Br

7 ve-

Halogen

MORE ATOMIC REPRESENTATIONS

RECALL: BOHR-RUTHERFORD MODEL

? What is the Rutherford-Bohr model for Argon?

? # protons: 18 ? # electrons: 18

Remember: Don't double up until

you've gone all the way around once!

18 p+

BOHR-RUTHERFORD MODEL

? As you can imagine, drawing out all the orbitals and all the electrons for some elements could be very tiring ? Imagine doing it for Oganesson (Og)...

Good thing you're only responsible for the first 20 elements!

LEWIS DOT DIAGRAMS

? When talking about chemical reactions, the only electrons we're really interested in are the valence electrons (the ones on the last shell)

? Along comes Gilbert N. Lewis (1916) and develops a simpler and quicker way to represent atoms (especially for showing how different elements bond to form compounds!)

? And it looks something like this...

Si

LEWIS DOT DIAGRAMS

? Dots are used to show the number of valence electrons an element has

? This means that all the elements in the same group have the same basic Lewis Dot diagram

? These dots are arranged in the 4 compass points (N, E, S,W)

? Again, you cannot double up until you've gone all the way around once! Examples:

OS

INCORRECT LEWIS DIAGRAMS

? The following are INCORRECT examples:

O Be F NO!

PRACTICE

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