Counting Atoms and Balancing Chemical Equations Write what is in Blue

Counting Atoms and Counting Atoms and Balancing Chemical EquationsBalancing Chemical Equations

Write what is in Write what is in BlueBlue

Elements, Compounds, Elements, Compounds, MixturesMixtures

Hydrogen is an element.Hydrogen is an element. Oxygen is an element.Oxygen is an element. When hydrogen and When hydrogen and

oxygen bond they make the oxygen bond they make the compound water.compound water.

When salt and water are When salt and water are combined, a mixture is combined, a mixture is created. Compounds in created. Compounds in mixtures retain their mixtures retain their individual properties.individual properties.

The ocean is a mixture.

Elements, compounds, and Elements, compounds, and mixturesmixtures

Mixtures can be separated by physical means.Mixtures can be separated by physical means. Compounds can only be separated by chemical Compounds can only be separated by chemical

means.means. Elements are pure substances. When the Elements are pure substances. When the

subatomic particles of an element are separated subatomic particles of an element are separated from its atom, it no longer retains the properties from its atom, it no longer retains the properties of that element.of that element.

Identifying CompoundsIdentifying Compounds

Each new element is identified by a capital Each new element is identified by a capital letterletter

Example: Example: HH22SOSO44

The elements in Sulfuric Acid The elements in Sulfuric Acid HydrogenHydrogenSulfurSulfurOxygenOxygen

SubscriptsSubscripts

CC1212HH2222OO1111

There are 12 atoms of CarbonThere are 12 atoms of CarbonThere are 22 atoms of HydrogenThere are 22 atoms of HydrogenThere are 11 atoms of OxygenThere are 11 atoms of Oxygen

If there is not a subscript listed, it is If there is not a subscript listed, it is understood to be 1.understood to be 1.

Example: Example: NaClNaClThere is one atom of SodiumThere is one atom of SodiumThere is one atom of ChlorineThere is one atom of Chlorine

You Practice!You Practice!

NaHCONaHCO33

Sodium – 1Sodium – 1

Hydrogen – 1Hydrogen – 1

Carbon – 1Carbon – 1

Oxygen -3Oxygen -3

HClHClHydrogen – 1Hydrogen – 1

Chlorine - 1Chlorine - 1

There are times you will see a compound There are times you will see a compound with parenthesis.with parenthesis.

Pb(NOPb(NO33))22

The 2 after the parenthesis indicates there The 2 after the parenthesis indicates there are two sets of the parenthesis. are two sets of the parenthesis.

Pb(NOPb(NO33) (NO) (NO33))

So, in counting the atoms, you would have So, in counting the atoms, you would have the following:the following:

Lead – 1Lead – 1 Oxygen - 6Oxygen - 6

Nitrogen -2Nitrogen -2

You Practice!!You Practice!!

(NH(NH44))33POPO44

Nitrogen – 3Nitrogen – 3


Phosphorus – 1Phosphorus – 1

Oxygen – 4Oxygen – 4

Mg(OH)Mg(OH)22

Magnesium – 1Magnesium – 1

Oxygen – 2Oxygen – 2


CoefficientCoefficient2H2H22SOSO44

This means there are 2 compounds of This means there are 2 compounds of Sulfuric Acid. Think:Sulfuric Acid. Think:

HH22SOSO44 HH22SOSO44

Counting the atoms:Counting the atoms:


Sulfur – 2Sulfur – 2

Oxygen - 8Oxygen - 8

You Practice!!You Practice!!

3H3H33POPO44


Phosphorus – 3Phosphorus – 3


2H2H22OO



Got It????Got It????

Chemical EquationsChemical Equations

Chemical equations express what is Chemical equations express what is happening in a chemical reaction using happening in a chemical reaction using symbols.symbols.

4K + Cl4K + Cl22 2KCl 2KCl

ReactantReactant Product Product

Law of Conservation of MassLaw of Conservation of Mass

In a chemical reaction, matter In a chemical reaction, matter cannot be created or cannot be created or destroyed. It can only be destroyed. It can only be changed.changed.

What does that mean??What does that mean??

The reactants MUST contain the The reactants MUST contain the same elements and the same same elements and the same number of each element as the number of each element as the product. They CAN be in different product. They CAN be in different compounds.compounds.

HUH?????HUH?????

HH22 + O + O22 HH22O O

Reactants: H = 2Reactants: H = 2 O = 2O = 2

Products: H = 2Products: H = 2 O = 1O = 1

This cannot happen. An oxygen atom This cannot happen. An oxygen atom cannot be destroyed.cannot be destroyed.

So what do we do?So what do we do?

The chemical equation must be written The chemical equation must be written according to the law.according to the law.

AGAIN --- HUH???AGAIN --- HUH???

HH22 + O + O22 HH22O is the production of O is the production of

water. Well, how it actually happens in water. Well, how it actually happens in nature is this….nature is this….

2H2H22 + O + O22 2H2H22OO

Reactants: H = 4 O = 2Reactants: H = 4 O = 2

Products: H = 4Products: H = 4 O = 2 O = 2

Do I Need to Know How to Do I Need to Know How to Balance?Balance?

NOT YET. You need to be able to NOT YET. You need to be able to recognize if the chemical reaction follows recognize if the chemical reaction follows the law of conservation of mass.the law of conservation of mass.

Na + ONa + O22 NaNa22O O

Mg + 2HCl MgClMg + 2HCl MgCl22 + H + H2 2

NOPE

YUP!!

You Practice!!!You Practice!!!

HgO Hg + OHgO Hg + O22

NN22 + 3H + 3H22 2NH2NH33

Zn + 2HClZn + 2HCl ZnClZnCl22 + H + H22

NOPE

YUP

YUP

More PracticeMore Practice

K + BrK + Br22 2KBr 2KBr

2Fe + O2Fe + O22 6Fe 6Fe22OO33

2Na + 2H2Na + 2H22OO 2NaOH + H2NaOH + H22

NOPE

NOPE

YUP

Got It???Got It???

Warm Up 3/9Warm Up 3/9Is it balanced? Show your work!!Is it balanced? Show your work!!

Al + OAl + O22 ---> Al ---> Al22OO33

SiClSiCl44 + H + H22O ---> HO ---> H44SiOSiO44 + HCl + HCl

Balancing Chemical EquationsBalancing Chemical Equations

HH22 + O + O22 HH22O O

Reactants: H = 2Reactants: H = 2 Products: H = 2 Products: H = 2

O = 2O = 2 O = 1 O = 1

What do we multiply by 1 to get 2?What do we multiply by 1 to get 2?

Keep Going….Keep Going….

HH22 + O + O22 22HH22O O

Reactants: Reactants: Products: Products: 2=H = 42=H = 4

2 =O = 2 =O = 22

Now the Oxygen is balanced but Hydrogen is not, Now the Oxygen is balanced but Hydrogen is not, so what do we multiply by 2 to get 4?so what do we multiply by 2 to get 4?

Almost There!!!Almost There!!!

22HH22 + O + O22 2H2H22O O

Reactants: Reactants: Products: Products:

4 4 H = 4 H = 4

2=O = 22=O = 2

Now it is balanced!!! Congratulations, you Now it is balanced!!! Congratulations, you have now learned the hardest thing we will have now learned the hardest thing we will do all year!!do all year!!

Now You PracticeNow You Practice

HgO HgO Hg + OHg + O22

=Hg ==Hg =

=O = =O =

K + BrK + Br22 2KBr 2KBr

=K = =K =

=Br = =Br =

Warm Up 3/11Warm Up 3/11Write Q&AWrite Q&A

Why do we have to balance equations? Why do we have to balance equations? (What law do we have to follow?)(What law do we have to follow?)


Balance the Following:Balance the Following:

HNOHNO3 3 + Ca(OH)+ Ca(OH)22 Ca(NO Ca(NO33))22 + H + H22O O

Warm Up 3/8Warm Up 3/8Write the Following:Write the Following:

The Law of Conservation of MassThe Law of Conservation of Mass

In a chemical reaction, matter In a chemical reaction, matter cannot be created or cannot be created or destroyed. It can only be destroyed. It can only be changed.changed.


How many atoms are in 3Pb(OH)How many atoms are in 3Pb(OH)4?4?

PbPbOOHH

Warm Up March 4Warm Up March 4Write Q&AWrite Q&A

The vertical columns on the periodic table The vertical columns on the periodic table are called ______________ and they are called ______________ and they correspond to the number of __________correspond to the number of __________

The horizontal rows on the periodic table The horizontal rows on the periodic table are called ____________ and they are called ____________ and they correspond to the number of __________correspond to the number of __________

Documents

Counting Atoms and Balancing Chemical Equations Write what is in Blue