valence electrons ppt.pdf, Exercises of Chemistry

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Atom – the smallest unit of matter “indivisible” Helium atom WHAT ARE THESE REGIONS CALLED AGAIN?

Remember

2 8 18

• the electrons of an atom that can participate in the formation of chemical bonds with other atoms
• THESE ARE THE OUTERMOST ELECTRONS IN THE ATOM!!!

Let’s Practice

• Elements in Group 1 should have how many valence electrons?
• Elements in Group 18 should have how many valence electrons?
• What about Group 16??? Pretty Simple, huh?

Electrons are placed in shells

according to rules:

1. The 1st shell can hold up to two electrons, and each shell thereafter can hold up to 8 electrons. For Example: Let’s say shell 3 has 8 valence electrons…it would be considered FULL even though it can hold a maximum of 18

Why are electrons important?

1. Elements have different electron configurations  different electron configurations mean different levels of bonding  When two or more atoms come together it creates a new substance called a COMPOUND  This just means that the way compounds are formed depends on how many valence electrons an atom has

Learning Check

**Give the ionic charge for each of the following: A. 12 p

and 10 e**

**-

1. 0 2) 2+ 3) 2- B. 50p

and 46 e-

1. 2+ 2) 4+ 3) 4- C. 15 p

and 18e-

2. 3+ 2) 3- 3) 5-**