matter & energy 1

Matter & Energy

• All things around you can be classified as matter, energy, or

both

• Matter and energy are interchangeable-proven by Einstein's

mass-energy equivalence equation

Matter

• Substance that comprises all physical objects

Characteristics:

• Occupies space

• Has mass

Not all:

• Has shape and form

• Has moving electrical charge (although 99.9% do)

• Is magnetic

Occupies space, Has mass

Characteristics of Matter

Mass (m)

• Primary characteristic

• Quantity of matter

• SI Unit: Kilogram (kg)

• Constant

Weight (w)

• Force an object exerts under gravity

• w=m*g

• SI Unit: Newton (N) or Pound (Ib)

• Not constant

Energy

• Ability to do work

• SI Unit: Joule (J)

• Radiology Unit: Electron volt (eV)

• Law of Conservation of Energy

• Can be transformed to different forms

• Cannot be created nor destroyed

The Atom

• Fundamental building block of matter

• Smallest particle of an elememt

Principal parts:

• Electrons

• Neutrons

• Protons

Greek, Dalton, Thomson, Rutherford, Bohr, Quantum Chromodynamics

Models of the Atom

Greek Atom

• Democritus

• Atomos - indivisible or uncuttable

Four substances:

• Earth, water, air, & fire

Four Essences:

• Dry, wet, cold, & hot

Dalton Atom

• John Dalton

• Hook and eye affair

• Compounds form when atoms combine in fixed ratios

• Atoms are solid, indivisible sphere

Thomson Atom

• J.J. Thomson

• Plum pudding

• Plum - electrons

• Pudding - shapeless mass of positive electrification

Rutherford Atom

• Ernest Rutherford

• Nuclear model

• Atoms contain a positively charge central nucleus

• Gold foil experiment

Bohr Atom

• Niels Bohr

• Planetary model

• Electrons orbit nucleus in fixed energy levels

• Hydrogen emission spectrum