Thursday 3 20 14
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Thursday 3-20-14. WU: 1. Draw an e-dot for the compound sodium nitride (Na bonded to N) 2. Today is the vernal equinox. a. Label the season for each of the Northern hemispheres in the picture. b. Explain how you know which one is the vernal equinox. 1. 4. 2.

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Thursday 3-20-14

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Thursday 3 20 14

Thursday 3-20-14

  • WU:

    1. Draw an e-dot for the compound sodium nitride (Na bonded to N)

    2. Today is the vernal equinox.

    a. Label the season for each of the Northern hemispheres in the picture.

    b. Explain how you know which one is the vernal equinox.

1

4

2

3


Thursday 3 20 14

Summer = tilted towards sun

Winter= tilted away from sun

Fall = from summer to winter

2. Today is the vernal equinox.

a. Label the season for each of the Northern hemispheres in the picture.

b. Explain how you know which one is the vernal equinox.

Spring = from winter to summer

1

4

2

3


Thursday 3 20 141

Thursday 3-20-14

  • WU:

    1. Draw an e-dot for the compound sodium nitride (Na bonded to N)


To do

To Do:

  • Grade Ions in Compounds Activity

  • Update SN

  • Writing Formula Notes

  • HW: Chemical Bonding Analysis


Thursday 3 20 14

Writing Chemical Formulas

Chemical formulas describe compounds and list the types & numbers of atoms that are present in the compound.

Consider the most famous chemical formula…

H2O

The small 2 is a subscript. It tells us that there are two hydrogen atoms in every molecule of water.

A subscript number always belongs to the atom on the left and can NEVER be changed in a chemical formula.


Thursday 3 20 14

H

H

O

Compounds form so that each atom has a full outer energy level

Sometimes that means it requires more than 1 atom to bond with another atom

H2O

Take water for example

Water requires 2 hydrogen's for each oxygen


Thursday 3 20 14

Given valence electrons figure out charge for each family

+1

0

+2

+/-4

-3

-2

-1

+3


Thursday 3 20 14

Always write metal first followed by nonmetal

Compounds always have a neutral charge

Sometimes that means you only need one metal and one nonmetal

Na+ + Cl- NaCl

Sometimes you need more than one metal &/or nonmetal

Ca+2 + Cl- + Cl-  CaCl2


Thursday 3 20 14

Find the number of atoms of Magnesium and Iodine needed to make Magnesium iodide.

Mg+2 + I-

+ I-

 MgI2

Find the formula for potassium nitride

K+ + N-3

+ K+ + K+ +

 K3N


Thursday 3 20 14

Cl Ca Cl

Criss Cross Method to find subscripts

If the charges do not already add up to zero, the charge # of the metal becomes the subscript for the nonmetal, and vice versa

For example: Calcium has a charge of 2, chlorine is a charge of 1 so the formula is CaCl2

= CaCl2

Ca+2 Cl-1

1

2

Ca+2 + Cl-1 + Cl-1 CaCl2

Of Course 1 atom is assumed and you don’t need that subscript


Thursday 3 20 14

Find the formula for magnesium phosphide

Mg+2 P-3

Mg+2 P-3

= Mg3P2

3

2

Mg+2 + Mg+2 + Mg+2 + P-3 + P-3 Mg3P2


To do1

To Do:

  • Update SN

  • Chemical Bonding Analysis


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