1. How Atoms Combine
SWBAT describe the chemical bonds that unite atoms to form compounds; describe the nature of chemical bonds that hold compounds together to the physical structures of compounds; distinguish among different types of mixtures and solutions

2. Definitions Compound Chemical bond Covalent bond
A substance that is composed of atoms of two or more different elements that are chemically combined
Chemical bond
The forces that hold elements together in a compound
Covalent bond
The attraction of two atoms for a shared pair of electrons

3. Molecular Attraction Molecules What charge to molecules have?
Composed of two or more atoms held together by a covalent bond
What charge to molecules have?
They don’t have a charge because the total number of protons and electrons are equal

4. Molecular Attraction Get out your lab notebooks
Send one person in your group to collect a cup of water, a penny, a nickel, and a dropper
Write the title and date in your lab notebook and as a group come up with a hypothesis for the following question
How many drops of water can a penny hold before the water overflows the side of the penny? How many will a nickel hold?

5. Molecular Attraction Procedure Place the penny on a paper towel
Gently squeeze drops of water onto the penny, counting how many drops hit the penny before overflowing. Record that number
Repeat this procedure 2 more times and calculate the average
Repeat the same procedure three times with the nickel

6. Molecular Attraction Glue the chart into your notebook
Answer the following in your lab notebook
Was there a difference in the number of drops of water the penny could hold for every trial? Why?
On average, how much more could a nickel hold than a penny?
Do you think a penny will hold the same amount of other liquids?

7. Molecular Attraction
Send one person in your group to get a cup of a different liquid.
Repeat the procedure on the penny with the new liquid
Share the results
Vinegar
Saltwater
Soapy water
Oil

8. Molecules
The chemical formula for molecules is written by listing the element of each atom and the number of them as a subscript.
H2O
2 Hydrogen, 1 Oxygen
CO2
1 Carbon, 2 Oxygen

9. Bonds
Polar bonds
Atoms in a covalent bond that do not share electrons equally
Negatively charged end
Positively charged end

10. Bonds Ion Ionic bond Metallic bond
An atom that gains or loses an electron
Ionic bond
The attractive force between two ions of opposite charge
Metallic bond
The valence electrons are shared by all the atoms, like a group of positive ions floating in a sea of negative electrons. It’s very conductive.

11. Charges How does an atom become positively charged?
When an atom has less than 4 valence electrons it can lose them. Because it loses a negative charge, it is no longer neutral, it has more protons than electrons.
How does an atom become negatively charged?
When an atom’s outer energy level is more than half full it can gain an electron giving it more negative particles than positive, and changing its charge

12. Chemical Reactions Chemical Reaction 6H2O + 6CO2 C6H12O6 + 6O2
The change of one or more substances into one or more substances
6H2O + 6CO C6H12O6 + 6O2
What is H2O?
What is CO2?
Does this equation balance?
What is it showing?

13. Mixtures and Solutions
Combination of two or more components that retain their identities
Heterogeneous mixture
Mixture where components are easily recognizable
Solution/Homogeneous mixture
The component particles cannot be distinguished

14. Mixtures Heterogeneous Salad Pepperoni pizza Fruit salad Homogeneous
Coffee
Atmosphere
Pudding

15. Acids and Bases Acid Base
A solution containing a substance that produces hydrogen ions (H+)
Has a pH of less than 7
Base
Produce hydroxide ions (OH-) in solution
Has a pH of greater than 7

16. Interpreting Scientific Illustrations
Magnesium Mg,
Sulfur S
A – 12, B – 16
Yes, Magnesium could lose its 2 valence electrons creating a positive ion (Mg2+), Sulfur could gain those 2 electrons, filling its outer energy ring and creating a negative ion (S2-)
Yes they could easily combine by sharing electrons, MgS