1. Ch 2 The Chemistry of Life
2.1 The Nature of Matter

2. Atoms Basic unit of matter
May be broken into smaller particles that do NOT have the properties of the element.

3. Atoms
Very small- 100 million atoms would make a row only about 1 centimeter long
Consists of protons, neutrons, and electrons.

4. Atoms Nucleus Protons Neutrons Electrons Core of atom
Positive charge, in nucleus, mass of 1 atomic unit
Neutrons
No charge, in nucleus, mass of 1 atomic unit
Electrons
Negative charge, orbits nucleus, mass of 0 atomic units (technically a mass of 1/1840).

5. Carbon Atom
Atoms have equal numbers of electrons and protons, their positive and negative charges balance out, and atoms themselves are electrically neutral.

6. Matter is made up of atoms Atoms join together to make compounds
Compounds use chemical bonds to hold them together
Chemical bonds are stored energy
Molecule
Atoms of the same element joined together.

7. Elements and Isotopes
Elements and isotopes have same number of electrons
All isotopes of an element have the same chemical properties.

8. Elements Pure substance that consists entirely of one type of atom or
Elements cannot be broken down into other types of substances
Mercury (Hg).

9. Isotopes
Atoms of the same element that differ in the number of neutrons.

10. Atomic Number (atomic mass or weight)
Number of protons
Atomic Number (atomic mass or weight)
Number of protons and neutrons.

11. Carbon Atom
Atomic Number 6
Mass Number 12

12. Radioactive Isotopes
Nuclei are unstable and break down at a constant rate over time
Used for
Determine the ages of rocks and fossils by analyzing the isotopes found in them
Detect and treat cancer
Kill bacteria that cause food to spoil
Labels or “tracers” to follow the movements of substances within organisms.

13. Chemical Compounds
Substance formed by the chemical combination of two or more elements in definite proportions
Water, the chemical formula H2O, contains two atoms of hydrogen for each atom of oxygen.

14. Chemical Compounds
Physical and chemical properties of a compound can be different from the elements that forms it
Sodium
Reacts explosively with cold water
Chlorine
Very reactive, poisonous, greenish gas that was used in battles during World War I
Sodium Chloride
Table salt.

15. Chemical Bonds
Attraction between two atoms resulting in a sharing or transferring of an electron(s)
Uses electrons
Covalent Bond
Chemical bond that SHARES electrons
Ionic Bond
Chemical bond that TRANSFERS electrons
Hydrogen Bond
Weak bond between hydrogen ions.

16. Covalent Bonds
Shares electron(s).

17. Ionic Bond Transfer of electron(s) Ion A charged particle
Protons do NOT equal electrons

18. Ionic Bond
A sodium atom easily loses its one valence electron and becomes a sodium ion (Na+).

19. Ionic Bond
A chlorine atom easily gains an electron (from sodium) and becomes a chloride ion (Cl-).

20. Van der Waals Forces
Slight attraction can develop between the oppositely charged regions of nearby molecules
Due to unequal sharing of electrons within each molecule
Much weaker than Covalent of Ionic bonds.