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Science-Physics 1 > Chemistry > Flashcards

Chemistry Flashcards

(79 cards)

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1
Q

What is an atom?

A

The smallest part of an element that can exist.

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2
Q

What is an element?

A

A substance made of only one type of atom.

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3
Q

How many elements are there?

A

About 100 different elements.

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4
Q

What is a compound?

A

A substance made from two or more elements chemically combined in fixed proportions.

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5
Q

What is a mixture?

A

Two or more elements or compounds not chemically combined.

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6
Q

How can mixtures be separated?

A

By physical processes, such as filtration, distillation, or chromatography.

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7
Q

What is a chemical formula?

A

A way to show which atoms and how many of each are in a molecule of a compound.

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8
Q

What is a word equation?

A

A way to write out what happens in a chemical reaction using the names of substances.

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9
Q

Give an example of a word equation.

A

Magnesium + oxygen → magnesium oxide.

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10
Q

What does filtration do?

A

Separates an insoluble solid from a liquid.

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11
Q

What is simple distillation used for?

A

To obtain a solvent from a solution (e.g. pure water from salty water).

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12
Q

What is fractional distillation used for?

A

To separate mixtures where components have different boiling points.

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13
Q

What is chromatography used for?

A

To separate mixtures of substances dissolved in a solvent, like inks or dyes.

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14
Q

Describe the setup for simple distillation.

A

Heat the solution so the solvent evaporates, travels through a condenser, and is collected; the solute stays behind.

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15
Q

Describe the setup for fractional distillation.

A

Heat the mixture, components with lower boiling points evaporate first and are condensed and collected.

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16
Q

Describe the setup for chromatography.

A

Place a spot of mixture on chromatography paper, solvent moves up carrying different substances at different rates, separating them.

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17
Q

What is meant by ‘physical process’ in separating mixtures?

A

Processes that do not involve chemical reactions and do not form new substances.

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18
Q

What is the law of conservation of mass?

A

The total mass of reactants equals the total mass of products in a chemical reaction.

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19
Q

How do you calculate the number of neutrons?

A

Number of neutrons = mass number - atomic number.

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20
Q

What is an isotope?

A

Atoms of the same element with different numbers of neutrons.

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21
Q

Give an example of two isotopes of chlorine.

A

Cl-35 (17 protons, 18 neutrons), Cl-37 (17 protons, 20 neutrons).

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22
Q

What is an ion?

A

An atom that has lost or gained electrons, giving it a charge.

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23
Q

How do metal atoms form ions?

A

They lose electrons to form positive ions.

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24
Q

How do non-metal atoms form ions?

A

They gain electrons to form negative ions.

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25
What is electron configuration?
The arrangement of electrons in shells around the nucleus.
26
How many electrons fit in the first shell?
Up to 2 electrons.
27
How many electrons fit in the second shell?
Up to 8 electrons.
28
How are electrons arranged in sodium?
2 in the first shell, 8 in the second, 1 in the third (total 11).
29
Name the three types of subatomic particles.
Proton, neutron, electron.
30
What is the charge and mass of a proton?
+1 charge, relative mass 1.
31
What is the charge and mass of a neutron?
0 charge, relative mass 1.
32
What is the charge and mass of an electron?
-1 charge, very small relative mass.
33
Where is almost all the mass of an atom found?
In the nucleus.
34
How are elements arranged in the periodic table?
In order of increasing atomic number.
35
What do elements in the same group have in common?
Similar properties and same number of electrons in their outer shell.
36
What are the Group 0 elements called?
Noble gases.
37
What are the Group 1 elements called?
Alkali metals.
38
What are the Group 7 elements called?
Halogens.
39
How does reactivity change in Group 1?
Increases down the group.
40
How does reactivity change in Group 7?
Decreases down the group.
41
What is relative formula mass (Mr)?
The sum of the relative atomic masses (Ar) of all the atoms in a compound.
42
What is an ionic equation?
An equation showing only the ions that change during a reaction.
43
Describe the development of the atomic model.
Started as tiny spheres, then plum pudding (positive sphere with electrons), then nuclear model (dense nucleus), then Bohr (electrons in shells), then modern model (protons & neutrons in nucleus).
44
What did the plum pudding model suggest?
Atoms are spheres of positive charge with electrons scattered through them.
45
What did Rutherford discover?
The atom has a small, dense, positive nucleus with electrons around it.
46
What is the nuclear model of the atom?
A small, dense nucleus containing protons and neutrons, with electrons in shells around the nucleus.
47
Define atom.
The smallest part of an element that can exist.
48
Define element.
A substance made of only one type of atom.
49
Define compound.
A substance made from two or more elements chemically combined.
50
Define mixture.
Two or more substances not chemically combined.
51
Define isotope.
Atoms of the same element with different numbers of neutrons.
52
Define ion.
An atom or group of atoms with a positive or negative charge.
53
What is alpha radiation?
A particle made of 2 protons and 2 neutrons (helium nucleus). Strongly ionising, weakly penetrating. Stopped by paper/skin. Causes mass number to decrease by 4 and atomic number by 2.
54
What is beta radiation?
A fast-moving electron. Moderately ionising, moderately penetrating. Stopped by a few mm of aluminium. Atomic number increases by 1, mass number unchanged.
55
What is gamma radiation?
An electromagnetic wave. Weakly ionising, highly penetrating. Stopped by thick lead or concrete. No change to mass or atomic number (just energy loss).
56
Compare the penetration of alpha, beta, and gamma radiation.
Alpha is stopped by paper/skin, beta is stopped by aluminium, gamma is stopped by thick lead/concrete.
57
Compare the ionising power of alpha, beta, and gamma radiation.
Alpha is most ionising, beta is moderate, gamma is least ionising.
58
What happens during radioactive decay?
An unstable nucleus emits alpha, beta, or gamma radiation to become more stable.
59
How does alpha decay change a nucleus?
Mass number decreases by 4, atomic number decreases by 2.
60
How does beta decay change a nucleus?
Mass number stays the same, atomic number increases by 1.
61
Does gamma decay change the nucleus?
No, it only releases energy with no change to mass or atomic number.
62
Why is alpha radiation dangerous inside the body?
It is strongly ionising and can cause a lot of damage to cells.
63
Why is gamma radiation dangerous outside the body?
It can penetrate the body and damage cells from the outside.
64
How are isotopes related to radioactive decay?
Unstable isotopes (radioisotopes) undergo radioactive decay and emit alpha, beta, or gamma radiation.
65
Model answer: Explain the differences between alpha, beta, and gamma radiation.
Alpha is a helium nucleus (2 protons, 2 neutrons), stopped by paper, strongly ionising, changes both mass and atomic number. Beta is a high-speed electron, stopped by aluminium, moderately ionising, changes atomic number only. Gamma is an electromagnetic wave, stopped by thick lead, weakly ionising, only releases energy.
66
Model answer: Explain what happens when an unstable isotope undergoes radioactive decay.
The unstable nucleus emits alpha, beta, or gamma radiation to become more stable. The atomic and mass numbers change depending on the type of decay. Energy is released as radiation.
67
Quick Test: Define the term 'atom'.
The smallest part of an element that can exist.
68
Quick Test: How is an element different to a compound?
An element contains only one type of atom; a compound contains two or more different elements chemically combined.
69
Quick Test: What does the formula CaCO₃ tell you about calcium carbonate?
It contains one calcium atom, one carbon atom, and three oxygen atoms per molecule.
70
Quick Test: What process can be used to extract pure water from salt water?
Simple distillation.
71
Quick Test: Describe the plum pudding model of the atom.
Atom is a sphere of positive charge with electrons scattered through it.
72
Quick Test: An atom of potassium has an atomic number of 19 and a mass number of 39. State the number of protons, neutrons, and electrons in this atom.
Protons = 19, neutrons = 20, electrons = 19.
73
Quick Test: An ion of potassium-39 has a +1 charge. State the number of protons, neutrons, and electrons in this ion.
Protons = 19, neutrons = 20, electrons = 18.
74
Quick Test: State the law of conservation of mass.
The total mass of reactants equals the total mass of products in a chemical reaction.
75
Quick Test: Calculate the relative formula mass of water, H₂O.
H: 1 x 2 = 2; O: 16 x 1 = 16; Total Mr = 18.
76
Quick Test: Calculate the relative formula mass of carbon dioxide, CO₂.
C: 12 x 1 = 12; O: 16 x 2 = 32; Total Mr = 44.
77
Quick Test: Calculate the relative formula mass of calcium nitrate, Ca(NO₃)₂.
Ca: 40; N: 14 x 2 = 28; O: 16 x 6 = 96; Total Mr = 164.
78
Quick Test: Why does the mass of the solid increase during some reactions?
The solid may absorb a gas from the air (e.g. magnesium reacts with oxygen to form magnesium oxide).
79
Quick Test: Why does the mass of the solid decrease during some reactions?
The solid may release a gas to the air (e.g. thermal decomposition of a carbonate releases CO₂).

Science-Physics 1 (3 decks)

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