Chapter 4 Test

Question 1

How do we construct a model of the atom since we can's see it?
1.
2.
3.
4.
5.

Answer 1

1. make observations
2. relate to past experiences
3. build a conceptual model
4. test the model (run experiments)
5. build on the model as more information becomes avaible

Question 2

Conservation of mass in a chemical reaction

1. atoms ______ to form new _______
2. bonds made up of ______ are broken & made
3. matter can neither be _____ or _______

Answer 2

1. rearrange, substances
2. electrons
3. created, destroyed

Question 3

What is an atom?

Answer 3

the smallest particle of an element that retains the properties of the element

Question 4

Schematic means…

Answer 4

electrons move from cathode to anode

Question 5

Plum pudding model

JJ Thompson

Answer 5

the view of the atom at this time was like plum pudding- all of the particles mixed together

Question 6

Atomic number-

Answer 6

the number of protons in an atom

Question 7

Neutral atoms-

Answer 7

number of electrons = number of protons

Question 8

Isotope

1. atoms with the same number of _____ but different numbers of ______
2. elements are found as mixtures of isotopes in _____

Answer 8

1. protons, neutrons

2. nature

Question 9

Mass number-

Answer 9

mass # = atomic # + # of neutrons

Question 10

Mass of atoms

1. _____ = 1.67 x 10^-24 g
2. ______= 1.67 x 10^-24 g
3. _______ are 1/1840 of a proton or neutron

Answer 10

1. proton
2. neutron
3. electron

Question 11

Atomic mass unit (amu)

Answer 11

1/12th the mass of a carbon^-12 atom

Question 12

Atomic mass of an element

Answer 12

The weighted average mass of the isotopes of that element. (Usually protons added with neutrons)

Question 13

Radioactivity-

Answer 13

Process where substances spontaneously emit radiation

Question 14

Radiation-

Answer 14

rays & particles emitted

Question 15

Nuclear reaction- involves change in an atoms ____

Answer 15

nucleus,

changing charge, properties, # protons, # electrons

Question 16

Radioactive decay= nuclei spontaneously _____ energy by emitting ______ that leads to stable nonradioactive atoms

Answer 16

lose, radiation

Question 17

Types of radiation;

1. Alpha- contains __ protons & __ neutrons
2. Beta- a process where a ______ becomes a ______ and an _____ is produced and emitted
3. Gamma- not a _____ but high-energy radiation/ possesses __ mass (very dangerous)

Answer 17

1. 2, 2
2. neutron, proton, electron
3. particle, no

Question 18

Atoms either gain or lose _____ in order to become stable again

Answer 18

neutrons

Question 19

Alpha

1. symbol;
2. mass (amu);
3. mass (kg);
4. charge;

Answer 19

1. (4/2) He or a
2. 4
3. 6.65 x 10^-27
4. 2+

Question 20

Beta

1. symbol;
2. mass (amu);
3. mass (kg);
4. charge;

Answer 20

1. e- or B
2. (1/1840)
3. 9.11 x 10^-31
4. 1-

Question 21

Gamma

1. symbol;
2. mass (amu);
3. mass (kg);
4. charge;

Answer 21

1. Y
2. 0
3. 0
4. 0

Question 22

How do the number of electrons and protons compare in a neutral atom? In a negatively charged atom? In a positively charged atom?

Answer 22

Neutral: # of electrons = # of protons
Negative: 1 proton = 2 electrons
Positive: 1 proton = 0 electrons

Question 23

Where are protons found? Neutrons? Electrons?

Answer 23

Protons - nucleus (+)
Neutrons - nucleus (no charge)
Electrons- outside nucleus (-) in electron cloud

Question 24

Describe the nucleus

Answer 24

dense & + charged region, core of the atom, protons & neutrons found there

Question 25

How do we write the name of an isotope? Give an example

Answer 25

carbon -12 ; 6p, 6n. carbon -14 ; 6p, 8n

Question 26

Understand the gold foil experiment. What happened when the alpha particles were aimed at the gold foil?

Answer 26

expected; alpha particles go straight through the gold foil

actual; some of the particles were deflected at different angles while others went through

Question 27

What is the law of conservation of mass? How was it related to the discovery of the structure of the atom?

Answer 27

Atoms rearrange to form new substances bonds made up of electrons are broken and made. Matter can neither be created nor destroyed

Question 28

What did Dalton’s atomic theory state?

1. all elements are composed of tiny, ______&________ particles
2. atoms of the same element are _________
3. atoms of different elements can combine in whole ratios in _____
4. chemical reactions occur when atoms _______

Answer 28

1. indivisible , indestructible (agreed with Dalton)
2. identical (not actually correct)
3. compounds (law of definite proportions)
4. rearrange

Question 29

What are the main components of the cathode ray? What happened with the alpha particles and this experiment?

Answer 29

cathode-negatively charged plates
anode-positively charged plates
cathode ray-emitted electrons
particles went from cathode to anode —> discovery of electron

Question 30

How many protons, neutrons, and electrons are in B-10

Answer 30

protons; 5, electrons; 5, neutrons;5

Question 31

How do the mass of a proton and the mass of a neutron relate? Proton and electron?

Answer 31

Mass of proton and neutron are the same.

Electron is 1/1840g of a proton and neutron

Question 32

Charges of alpha, beta, and gamma particles

Answer 32

alpha- 2+
beta - 1-
gamma- 0