Unit One

Question 1

Proton

Answer 1

p+
Located in nucleus
Relative charge = +1
Mass = 1.673x10^-24

Question 2

Neutron

Answer 2

n0
Located in nucleus
Relative charge = 0
Mass = 1.673x10^-24

Question 3

Electron

Answer 3

e-
Located in electron cloud
Relative charge = -1
Mass = 9.11x10^-28

Question 4

Mass and volume of atom

Answer 4

Mass = protons and neutrons
Volume = electron cloud

Question 5

Atomic number

Answer 5

The number of protons in an atom
Identifies the element
Periodic table organized by increasing atomic number
Based on charge of atom, can calculate protons and electrons
Charges written after element symbol (K+, Fe-2)

Question 6

Charges of atoms:
Neutral
Positive
Negative

Answer 6

Neutral: protons = electrons
Positive: protons > electrons
Negative: protons

Question 7

Mass number

Answer 7

Number of protons and neutrons, technically it is not found on the periodic table (for simplicity often round decimal to nearest whole number)

Question 8

Isotopes

Answer 8

Atoms of the same element that have different numbers of neutrons
Always have the same atomic number but different mass numbers

Question 9

Atomic mass

Answer 9

The weighted average of all the isotopes for a given element based on their frequency in nature
The atomic mass is the decimal number recorded on the periodic table for each element
Atomic mass listed on the periodic table is not the same as the mass number

Question 10

Carbon-14

Answer 10

14 is the mass number

Question 11

16
O
8

Answer 11

16 is the mass number

8 is the atomic number

Question 12

Atom

Answer 12

The smallest identifiable unit of matter that makes up all things

Question 13

Democritus

Answer 13

Major contribution: the atom
Proposed that everything was made of these atoms and they were all indivisible
Theory correct except that atoms are divisible

Question 14

John Dalton

Answer 14

Major contribution: the atomic theory, with the following five principles
1. All things are composed of indivisible particles called atoms
2. All atoms of a certain element are identical
3. Atoms of different elements are different
4. Compounds are formed when atoms of two or more elements chemically combine in whole number ratios
5. During chemical reactions, atoms can be combined, separated, or rearranged, but never created or destroyed
Theory correct except that atoms are divisible and that atoms of the same element can be different because isotopes

Question 15

Law of definite proportions

Answer 15

A compound is always composed of the same elements in the same proportion by mass

Question 16

Law of multiple proportions

Answer 16

It is possible for atoms of two different elements to combine in different ratios, however if the ratio is changed, it is a different compound.

Question 17

JJ Thomson

Answer 17

Major contribution: the electron
Cathode ray tube experiment (deflecting plates, discovered negative charge because particles deflected towards positive plate), Nobel prize
Plum pudding model: positively charged atom with randomly dispersed negative electrons
Theory not correct because missing parts of atom

Question 18

Ernest Rutherford

Answer 18

Major contributions: the nickels and that the atom is mostly empty space
Gold foil experiment (shot particles at gold foil, some went through, some deflected–concluded that there was a nucleus)
Atomic model is a circle with stuff in it
Theory mostly correct except missing neutrons and the location of the electrons

Question 19

Niels Bohr

Answer 19

Major contribution: planetary model of the atom
Observed that when light was given off from an atom, there were only single lines visible, proposed that each line represented an electron in a different orbit
Planetary model, with nucleus, and electrons in orbit lines around atom
Mostly correct except for placement of electrons

Question 20

Current theory of the atom (quantum mechanics)

Answer 20

Electron cloud mode
Cloud is an area of probability where the electron is
Electrons move at extremely high speeds, occupy the entire area of the cloud (can’t know speed and place at same time)

Question 21

Radioactivity

Answer 21

The process by which an unstable nucleus emits particles or energy to become more stable
Any atomic numbers greater than 83 are unstable

Question 22

Half-life

Answer 22

The amount of time required for a decaying substance to lose half of its original amount

Question 23

Alpha decay

Answer 23

Type of decay in which a helium nucleus is emitted
4
   He or half infinity signs
2 
Heaviest form of nuclear decay
Low penetrating power
Positive charge

Question 24

Beta decay

Answer 24

Type of decay in which an electron is emitted
0
e or β
-1
Much lighter than an alpha particle because it is very fast
Moderate penetrating power
Negative charge

Question 25

Gamma decay

Answer 25

Type of decay in which large amounts of energy are emitted from a nucleus. Often emitted along with alpha or beta particles.
0
   g or squiggly thing
0 
No mass or charge
Very high penetrating power

Question 26

Fission

Answer 26

When the nucleus of an atom splits in order to form a more stable nucleus
Used in nuclear power plants

Question 27

Fusion

Answer 27

The combining of smaller nuclei into larger ones

Used in stars