1. Warmup What is the name and symbol of this atom?
What is it’s atomic #?
Mass #?
Atomic mass?
Can you draw the
electron rings around it?
19 protons
20 neutrons

2. Ionic: very strong, creates solids.
3 types of bonds
Ionic: very strong, creates solids.
Polar: medium strength bond. Some solids, liquids, and gases
Covalent: very weak bond. Some solids, liquids, gases

3. Bond type depends on how electrons are shared between atoms
Electronegativity: An atom’s attraction for electrons
High EN = strong attraction
Low EN = low attraction

4. How to figure out bond type:
You must calculate at the electronegativity difference between the two atoms
Use the approximate guideline for electronegativity differences:
0.0 – < 0.5 = covalent (electrons shared nicely)
0.5 – < 2.0 = polar covalent (electrons being pulled from stronger atom)
2.0 – 4.0 = ionic (electrons stolen/transferred by stronger atom

5. Use these values provided to help:

6. Examples:
H and Cl
2.1 – 3.0
Difference = 0.9 = polar
C and H
2.5 – 2.1
Difference = 0.4 = covalent

7. Examples: Na and Cl 0.9 – 3.0 Difference = 2.1 = ionic
Also notice that you have a metal bonded to a nonmetal!
Follow this link for a video recap:
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8. Atoms: # protons = # electrons Ions: # protons ‡ # electrons
Atoms vs. ions
Atoms: # protons = # electrons
Atoms are neutral (no charge)
Ions: # protons ‡ # electrons
Electron has been ripped off by stronger EN atom
Ions have either a positive or negative charge.
Ions are atoms that have gained or lost electrons.

9. WhY do atoms gain/lose electrons?
All atoms want to look like a noble gas.
Noble gases are “inert” = non-reactive
Why don’t they react?
They have full valence electron
shells.
All noble gases (except He) have
8 valence electrons!
So all other atoms will either gain or
lose electrons to have 8 valence electrons, too!

10. Cations: atoms that have LOST electrons and have a POSITIVE charge.
Two types of ions
Cations: atoms that have LOST electrons and have a POSITIVE charge.
Anions: atoms that have GAINED electrons and have a NEGATIVE charge.

11. Has 11 protons and 11 electrons. Draw the electrons in:
Example #1: sodium
Sodium: atomic #11
Has 11 protons and 11 electrons.
Draw the electrons in:
11 p+
Remember:
1st ring: 2 electrons max
2nd ring: 8 electrons max
3rd ring: 18 electrons max

12. Example #1: sodium Notice that this atom has 1 valance electron.
Sodium has 2 choices: lose 1
electron to look like Neon
Or gain 7 more electrons to be
like Argon.
Atoms are lazy…they take the
easiest option!
Sodium will LOSE 1 ELECTRON!
11 p+

13. What does sodium look like now? Still has 11 protons
Example #1: sodium
What does sodium look like now?
Still has 11 protons
Now has only 10 electron
Protons are positive
Electrons are negative
(+11)+(-10) = +1 charge
11 p+

14. Has 17 protons and 17 electrons. Draw the electrons in:
Example #2: Chlorine
Chlorine: atomic #17
Has 17 protons and 17 electrons.
Draw the electrons in:
17 p+
Remember:
1st ring: 2 electrons max
2nd ring: 8 electrons max
3rd ring: 18 electrons max

15. What does chlorine want to do?
Chlorine has 2 choices:
Lose all 7 valence electron
Gain 1 more valence electron
Much easier to just gain 1
17 p+

16. What does chlorine Look like now?
Still has 17 protons
Now has 18 electrons
(+17)+(-18) = -1 charge
17 p+

17. What happens when sodium and chlorine “find” each other?
Notice sodium has 1 extra electron to give away and chorine WANTS one electron?
11 p+
17 p+
sodium
chlorine

18. Ionic bonding
One atom must lose electrons (it’s always the metals on the periodic table)
Caton (positive)
One atom must gain electrons (it’s always the nonmetals on the periodic table)
Anion (negative)
Metal + nonmetal = ionic bond
Positive + negative attract!