Chapter 3 - The Atomic Nucleus

Question 1

What is a theory?

Answer 1

Explanations of an aspect of science that has been tested over time.

Question 2

What is an atom?

Answer 2

The smallest unit of matter

Question 3

How is the overall atom charged?

Answer 3

Neutrally

Question 4

How is the proton charged?

Answer 4

Positively

Question 5

How is the electron charged?

Answer 5

Negatively

Question 6

How is the neutron charged?

Answer 6

Neutrally

Question 7

Democritus

Answer 7

The Greek philosopher who came up with the concept of the atom/atomic theory.
- He stated that rocks could be broken down essentially until they couldn’t be.
- Called the smallest part of matter “atomos,” meaning “indivisible.”

Question 8

What did Dalton’s atomic model look like?

Answer 8

A billiard ball - the atom was dense and spherical like pool balls.

Question 8

Antoine Lavoisier

Answer 8

The Law of Conservation of Mass
- Mass cannot be created or destroyed in a reaction.

Question 9

Joseph Proust

Answer 9

Law of Definite Proportions
- Elements combine in specific ratios
- Different ratios of the same compound
- Example: Co2 can be combined in several ratios, including 1:2 (0.50), 12:16 (0.75) , and 24:32 (0.75)

Question 10

John Dalton

Answer 10

Law of Multiple Proportions
- Elements combine in different fashions.
- Example: Co2 = Carbon dioxide, and Co = Carbon monoxide; two completely different compounds

Question 11

Contradictions to Dalton’s Postulates?

Answer 11

1) An atom is NOT the smallest particle of matter
2) Atoms are made up in several subatomic particles which are identical in all atoms

Question 11

What are Dalton’s Five Postualtes?

Answer 11

1) Atoms are indivisible + the smallest things
2) Atoms of the same element are identical
3) Law of Conservation of Mass
4) Law of Multiple Proportions
5) In chemical reactions, atoms are rearranged, separated, or combined.

Question 12

What determines atomic properties and type?

Answer 12

The way subatomic particles are put together

Question 13

Three basic subatomic particles

Answer 13

1) Proton - Positive particle - mass of 1
2) Neutron - Neutral particle - mass of 1
3) Electrons - Negative particle - mass of about 0

Question 14

An atom is _______________, but take away an _________________ or ____________________, and this becomes unbalanced.

Answer 14

1) neutral
2) electron
3) proton

Question 15

J.J. Thomson

Answer 15

• Cathode Ray Tube Experiment - Discovered the electron
• Plum Pudding Model - Negative particles sprinkled throughout the empty positive space of the atom.

Question 16

Ernest Rutherford

Answer 16

• Gold Foil Experiment - Discovered the positive nucleus of the atom, with the rest being empty space.

Question 17

Niels Bohr

Answer 17

Planetary Model - The electrons orbited around the positive, tiny nucleus at the center of the atom in energy levels, like the planets around the sun.

Question 18

Robert A. Milikan

Answer 18

Oil Drop Experiment - Proved the electrons’ negative charge

Question 19

Difference of Hyphen Notation and the Nuclear Symbol

Answer 19

Hyphen Notation
- Element (dash) mass number

Nuclear Symbol
- Element Abbreviation
- Mass (top, right hand side)
- Atomic Number (bottom, right hand side)

Question 20

What is an isotope?

Answer 20

Atoms of the same element with different mass and neutron numbers

Question 21

How are isotopes of the same element alike?

Answer 21

1) Same protons
2) Same electrons
3) Same atomic number
4) Same element

Question 22

What is average atomic mass?

Answer 22

The weighted average of all naturally occurring isotopes found in nature
- Measured in amu

Question 23

How to calculate average atomic mass?

Answer 23

1) Make percents into decimals (divide by 100)
2) (Mass of isotope 1 x percentage as decimal) + (Mass of isotope 2 x percentage as decimal) + (Mass of isotope 3 x percentage as decimal) and so forth.