chapter 3 atomic structure democritus greek philosopher 470-380 bc deduced the ‘atom’ –greek...

Chapter 3

Atomic Structure

DEMOCRITUS

• Greek philosopher• 470-380 BC• Deduced the ‘atom’

– Greek for

• Everything in universe is made of

Lavoisier

•

• Concluded a chemical reaction

Proust

• Law of

• A given compound always has the same ratios of elements

•

Dalton

• Atomic theory of matter

•

Dalton’s Postulates

• Each element is

• All atoms of a given element are

Dalton’s Postulates

• Atoms are

• A given compound always

How did he know?

• Indirect evidence

• Observations on how things reacted

Scanning Tunneling Microscope

• Atoms in Silicon

Structure

• Michael Faraday• Proved atoms

contained

Ben Franklin

• Studied static electricity

• Flew a kite in a thunderstorm

• Don’t do this at home

• Concluded 2 charges

Charges• Positive (+) • Negative (-)• Like charges • Opposite charges • Built up

• When the electrons jump to a door or person…

Cathode Rays

• TV

• Electrons moving through a glass tube with little pressure inside.

• J.J. Thompson

Atomic Structure Review

• Proton–

• Neutron–

• Electron–

The Modern Day Atom• Nucleus:

–

–

• Orbiting Nucleus:–

Atomic Numbers (Z)• Equal to • NEVER CHANGES

Mass Number (A)• Sum of

Isotopes of the Elements• Same

• Different number of

Isotopes

• Defined:–

• Will have different mass

• C-12

• C-13

Average Atomic Mass

• Ave Mass =

• No

• No

• Only

Practice

• What is the average atomic mass of the following element. Isotope/mass Abundance

Q-54 43%

Q-55 29%

Q-53 17%

Q-56 11%

Ions of the Elements

• Same number of

• Has lost or gained –Contains

Practice

• How many electrons in