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Chemistry > Chapter 4 > Flashcards

Chapter 4 Flashcards

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1
Q

Suggested that if you divide matter into smaller and smaller pieces, you end up with tiny indestructible particles called atoms (meaning indivisible).

A

Democritus

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2
Q

Responsible for the Law of Conservation of Mass:

A

Antione Lavoisier

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3
Q

What is the Law of Conservation of Mass?

A

In a chemical reaction, matter is neither created nor destroyed. The total amount of matter stays constant.

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4
Q

Responsible for the Law of Definite Proportions:

A

Joseph Proust

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5
Q

What is the Law of Definite Proportions?

A

A compound is always composed of the same elements in the same proportion by mass, no matter how large or small the sample. Salt is salt.

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6
Q

Responsible for the Law of Multiple Proportions?

A

John Dalton

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7
Q

What is the Law of Multiple Proportions?

A

When different compounds are formed from a combination of the same elements, different masses of one element combine with the same fixed mass of the other element in a ratio of small whole numbers.

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8
Q

Who proposed the Atomic Theory?

A

John Dalton

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9
Q

What was the Solid Sphere Model and who developed it?

A

John Dalton
* Each element is composed of tiny, indestructible particles called atoms
* All atoms of a given element have the same mass and other properties that distinguish them from the atoms of other elements
* Atoms combine in simple, whole number ratios to form compounds
* In chemical reactions, atoms are combined, separated, or rearranged. Atoms of one element cannot be changed into atoms of a different element as a result of a chemical reaction.

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10
Q

What are the three fundamental parts of an atom?

A

Proton, Neutron, Electron

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11
Q

Who discovered the electron using the cathode ray tube?

A

J.J. Thomson

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12
Q

What was the cathode ray experiment?

A

Electricity was passed through a vacuum sealed tube. When charged plates were brought close to the tube, the beam of electricity reacted by moving towards the positively charged plate and away from the negatively charged plate. A magnet also deflected the cathode ray.

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13
Q

Who calculated the mass of an electron and determined its charge?

A

Robert Millikan

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14
Q

Who introduced the plum pudding model and what was it?

A

J.J. Thomson; Negatively charged electrons must be held in a sphere of positive charge

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15
Q

Who conducted the famous oil-drop experiment?

A

Robert Millikan

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16
Q

What was determined to be the smallest common denominator for the charge of an electron?

A

1.602x10^-19 coulombs

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17
Q

The mass of an electron is approximately 1/ ____ the mass of a proton.

A

1840

18
Q

Who and why did _________ ___________ perform his gold foil experiment?

A

Ernest Rutherford: He was trying to study how positively charged particles interacted with solid matter

19
Q

What unexpected result came from the gold foil experiment?

A

A small number of alpha particles were deflected or bounced back, hinting to a positive charge in the nucleus

20
Q

Who came up with the Nuclear Model of the Atom?

A

Ernest Rutherford

21
Q

Where is most of an atom’s mass contained?

A

In the nucleus

22
Q

Most of the _________ of the atom is empty space through which tiny, negatively charged electrons are dispersed.

A

Volume

23
Q

The number of protons in a neutral atom are equal to the number of __________.

A

Electrons

24
Q

Who discovered evidence of neutrons?

A

James Chadwick

25
Q

Who arranged the periodic table in order of increasing number of protons (or atomic number)?

A

Henry Moseley

26
Q

Elements are defined by their number of ____________.

A

Protons

27
Q

Atoms with the same number of protons but differing numbers of neutrons are called ___________.

A

Isotopes

28
Q

When written as Carbon-12, the number is the _______ number.

A

Mass

29
Q

The average atomic mass is the weighted average of all the naturally occurring _______ of that element.

A

Isotopes

30
Q

Protons and Neutrons each have a mass close to __ amu.

A

1

31
Q

Why are neutrons important in a nucleus?

A

Positive charges repel against each other. Neutrons space out protons enough so that the nucleus doesn’t blow itself apart immediately. They are there for stability.

32
Q

Vocab term: The process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves

A

Radioactive decay

33
Q

Vocab term: The particles that are released from the nucleus during radioactive decay

A

Nuclear radiation

34
Q

In a (chemical, nuclear) reaction, the nucleus always changes thus changing the identity of the atom.

A

Nuclear

35
Q

How many protons and neutrons are in an alpha particle? (Identical to a Helium nucleus)

A

2 protons, 2 neutrons

36
Q

True or false: alpha particles are so massive they can barely travel through a piece of paper

A

True

37
Q

What is a beta particle?

A

A fast-moving electron that is ejected from the nucleus. Beta decay occurs when a neutron changes into a proton and electron.

38
Q

True or false: Beta particles cannot easily go through paper and are stopped by aluminum or wood.

A

False, they can go through paper but not aluminum or wood

39
Q

What are gamma rays?

A

They are not charged particles, rather they are a type of high electromagnetic radiation. Gamma rays are a result of alpha and beta decay not releasing enough energy and gamma releases the excess.

40
Q

True or false: Gamma rays are mostly blocked by lead and have more energy than light or X-rays

A

True

41
Q

Vocab term: The time for half of the radioactive nuclei in a given sample to undergo decay

A

Half-life

Chemistry (3 decks)

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