1. What is the world made of, and how is it all held together?

2. Nothing…
…if the earth is the nucleus of an atom, the electrons are twice as far away as pluto

3. protons neutrons electrons
CB 2.4
Atoms are made of:
protons neutrons electrons

4. CB 2.8
Each element is defined by the number of protons, has an equal number of electrons, the number of neutrons may vary.

5. The Periodic Table of the Elements

6. Atoms can be combined together to make molecules

7. How do atoms form molecules?

8. An atom’s chemical characteristics are determined by the number of electrons it has.

9. Bonds holding atoms together:
Covalent
Strong
Sharing Electrons
When broken = chemical reaction
energy consumed or released
Ionic
Weak
Positive and Negative atoms attracted to each other

10. CB 2.13
Ionic bonds- electrons donated/accepted then atoms attracted by opposite charge

11. Ionic bonds are easily broken

12. Bonds holding atoms together:
Covalent
Strong
Sharing Electrons
When broken = chemical reaction
energy consumed or released
Ionic
Weak
Positive and Negative atoms attracted to each other

13. Covalent bonds- atoms share electrons
CB 2.11
Covalent bonds- atoms share electrons

14. a chemical reaction makes or breaks covalent bonds
CB 8.14
a chemical reaction makes or breaks covalent bonds

15. Electron sharing in a covalent bond is not always equal
CB 2.12
water + +

16. polar versus non-polar molecules +
CB 2.12
polar versus non-polar molecules + H H C + H + + H + +
water
methane

17. Bonds holding atoms together:
Covalent
Strong
Sharing Electrons
When broken = chemical reaction
energy consumed or released
Ionic
Weak
Positive and Negative atoms attracted to each other

18. Four types of molecules that are primarily found in living systems (biomolecules):
Carbohydrates/ Sugars
Nucleotides- DNA/RNA
Amino Acids- Proteins
Lipids- fats/phospholipids
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19. CB 6.2