1. Matter

2. Origins of the Idea Democritus (~400 BCE)
Matter is composed of atoms
Atoms are eternal, invisible, indivisible, and incompressible
Greeks believed in 3 phases or states of matter
Solid, liquid, gas
We now add plasma as the fourth phase

3. Matter in the Universe
99% of the known matter in the universe is Hydrogen and Helium
The majority of the known matter is in the form of a plasma in stellar interiors
The average density of the known matter in the universe is such that 1 gram would occupy a volume 30 x that of Earth
The location and characteristics of most of the matter in the universe is unknown – dark matter

4. Antimatter
A matter particle and an antimatter particle are the same with the exception of charge and magnetic properties (which are opposite).
Naturally formed and man-made.
When matter and antimatter particles collide, they annihilate each other.

5. Elements Fundamental forms of matter
Can’t be broken apart by normal means
92 occur naturally on Earth
They are the same everywhere

7. What Are Atoms?
Smallest particles that retain the distinguishing physical and chemical properties of an element
Made up of subatomic particles:
Protons (+)
Electrons (-)
Neutrons (no charge)

8. Examples of Atoms
electron
proton
neutron
Hydrogen
Helium

9. Chemical Bonds, Molecules, & Compounds
Bond is union between electron structures of atoms
Atoms bond to form molecules
Molecules may contain atoms of only one element - O2
Molecules of compounds contain more than one element - H2O

10. Atomic Number 6C12 6C13 6C14 Number of protons
All atoms of an element have the same atomic number
Atomic number of hydrogen = 1
Atomic number of carbon = 6

11. Isotopes vary in mass number
6C12 6C13 6C14
Number of protons +
Number of neutrons
Isotopes vary in mass number

12. Isotopes
Atoms of an element with different numbers of neutrons (different mass numbers)
Carbon 12 has 6 protons, 6 neutrons
Carbon 14 has 6 protons, 8 neutrons
6C12 6C13 6C14

13. Chemical Origins
Most chemical elements were created after the Big Bang in subsequent generations of stars.
Nucleosynthesis:
primordial (H, He, Li)
stellar (He -> Fe)
explosive (Co -> …)

14. Radioisotopes - Radioactivity
Have an unstable nucleus that emits energy and particles
a particles – 2 protons and 2 neutrons
b particles – an electron
g rays – a high energy photon
Radioactive decay transforms radioisotope into a different element
Decay occurs at a fixed rate
Because decay happens at a fixed rate, you can use it for age dating! (C14 has a half-life of 5,700 years.)

15. The Age of the Solar System
Ages of rocks can be measured through radioactive dating:
Measure abundance of a radioactively decaying element to find the time since formation of the rock
Dating of rocks on Earth, on the Moon, and meteorites all give ages of ~ 4.6 billion years.