Unit 2: The Atom

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58 Terms

1
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what is an atom?

the smallest unit of matter

2
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what is an atom made of?

protons, neutrons, electrons

3
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what are the characteristics of a proton

positive charge, in the nucleus, has mass, and identifies the element

4
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what are the characteristics of a neutron

neutral charge, in the nucleus, has mass, and stabilizes the nucleus

5
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what are the characteristic of an electron

negative charge, in the shells of the atom, no relative mass, and involved in bonding

6
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what is average atomic mass

the weighted average of all the different isotopes of an element - unit: amu

7
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how do you find the # of neutrons in an atom?

rounded atomic mass - protons = neutrons

8
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what is an isotope

atoms of the same element with different numbers of neutrons

9
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what does mass number represent

the number of protons and neutrons in an atom

10
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what are ions

atoms that gain or lose electrons when becoming charged particles

11
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what is a cation

atom loses electrons and it becomes positively charged. ex: Na^+

12
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what is an anion

a gain in electrons which makes it negatively charged. ex: Cl^-

13
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how do you know what version of an element is most abundant?

the one closest to the average mass

14
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what is a half-life

the time required for a substance to decay by half (t1/2)

15
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which is consistent in half-life decay: the percent decrease or the number decrease?

percent - b/c the number changes

16
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what are the 3 types of decay

alpha, beta, gamma

17
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why do elements go through these 3 types of decay?

to become more stable

18
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what is the symbol for alpha

fish looking thing

19
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what is the symbol for beta

B with tail

20
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what is the symbol for gamma

loopy y

21
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what charge does alpha have?

positive

22
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what charge does beta have?

negative

23
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what charge does gamma have?

no charge

24
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is alpha, beta, or gamma the biggest?

alpha

25
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what elements primarily use alpha decay?

element numbers 83+

26
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what happens to the atom when it goes through alpha decay?

It releases protons and neutrons. The mass decreases by 4 (top), and the atomic number decreases by 2 (bottom)

27
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what element is associated with alpha?

helium (He)

28
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what happens to the atom when it goes through beta decay?

the isotope releases an electron and the atomic number increases by 1

29
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are protons or electrons associated with beta?

electrons

30
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what happens to the atom when it goes through gamma decay?

an isotope releases gamma rays. nothing changes about the atom but it moves to a stable energy level

31
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what is penetrating power

how easily each type of radiation can pass through different materials

32
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do smaller or larger atoms have higher penetrating power?

smaller (easier to pass through a substance)

33
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what is ionizing power

the ability of radiation to damage molecules

34
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do larger or smaller particles cause more damage to the substance they enter?

large

35
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what is fission

the breaking apart of atoms

36
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what is fusion

the combination of 2 atoms

37
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what is the nickname for the atomic bomb

fission bomb

38
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what is the nickname for the hydrogen bomb

thermonuclear bomb

39
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what elements are involved with the reactions of the bombs?

U (uranium) and Pu (plutonium)

40
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is the atomic bomb or hydrogen bomb stronger?

hydrogen

41
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how is fission involved in the hydrogen bomb?

it creates the conditions for fusion to occur

42
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what is carbon dating?

using the known rate of decay to date a fossil using carbon

43
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what version of carbon is used in carbon dating

carbon-14

44
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would an older fossil have more or less carbon?

less

45
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democritus

- found matter is made of small, indivisible particles called atoms.

-model: solid sphere

46
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john dalton

- elements are made of unbreakable particles called atoms (wrong)

-atoms of the same element are identical in every way (wrong)

-atoms combine in simple whole number ratios to form compounds

-chemical reaction involves rearrangement of atoms, not a complete change

47
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dmitri mendeleev

-created the periodic table in 1869

-discovered a pattern in elements

48
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jj thomson

-discovered the first subatomic particle: electron

-the electron is negatively charged

-performed the cathode ray tube experiment

-model: plum pudding

49
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Cathode Ray Tube Experiment

he put a magnet on the vacuum tube and saw that it was attracted to the positive side meaning that it was negatively charged

50
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ernest rutherford

-discovered that all positive charge is located in a tiny, dense core: the nucleus

-did the Gold Foil Experiment

- nuclear model (first one with a nucleus)

51
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Gold Foil Experiment

shot alpha particles at thin gold foil, most went straight through showing that there it is mostly open space, and some deflected meaning there was a small, dense, positive charge in the core

52
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niels bohr

-planetary model

-electrons orbit the nucleus and everything has its place - they can jump between but always on one

53
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erin schrodinger

-quantum model

-found that electrons exist in shells/clouds of various shapes called orbitals

54
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james chadwick

-discovered the neutron is in the nucleus and that it has no charge

55
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what is Avogadro´s number

6.022×10²³

56
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what is molar mass

the mass of 1 mol of a substance

57
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what is the symbol (unit) for molar mass

g/mol

58
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where do you find what the molar mass of an atom is?

its atomic mass