C1 Particles Flashcards

1
Q

Name three examples of particles in chemistry

A

Atoms, ions, molecules, compounds

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2
Q

Describe the main difference between the arrangement of particles in the liquid state and particles in the gas state

A

Liquid:
Particles move around each other
Medium forces of attraction
Fixed volume
Gas:
Particles move freely
No forces of attraction
No fixed volume
No fixed shape

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3
Q

Explain why you can compress a substance in the gas state

A

Since gas has no fixed volume, it can move freely and so will move into space

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4
Q

Explain why a solid expands when it is heated

A

When a solid is heated, its forces of attraction begin to break down and it is able to move slightly, so the particles move away from each other

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5
Q

What is a physical change?

A

A change of state that can (generally) easily be reversed. The arrangement and number of particles and atoms are not changed. No new products are made

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6
Q

What is a chemical change?

A

A change that produces one or more new substances. Different particles react with each other to form different products. They are usually hard to reverse.

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7
Q

What are the advantages of the particle model?

A

It shows the arrangement of the atoms in all three states of matter

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8
Q

What are the disadvantages of the particle model?

A

The distance between the particles (in the gas state)
It does not show the forces/movement of particles
It is 2D when particles are 3D

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9
Q

What keeps particles close together in liquids?

A

Electrostatic forces of attraction

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10
Q

What is the charge and mass of a proton?

A

+1, 1

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11
Q

What is the charge and mass of an electron?

A

-1, 0.0005

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12
Q

What is the charge and mass of a neutron?

A

0,1

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13
Q

Why is most of an atom’s mass in its nucleus?

A

The nucleus is where the protons and neutrons are, which weigh far more than the electrons orbiting it.

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14
Q

How many times bigger is the radius of an atom compared to the radius of its radius?

A

100,000 times

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15
Q

Describe the structure of an atom

A

A nucleus of protons and neutrons orbited by electrons in fixed electron shells.

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16
Q

How many times greater is the mass of a proton compared to an electron?

A

2000 times

17
Q

What is an isotope?

A

Atoms of an element with the same number of protons and electrons but different numbers of neutrons

18
Q

Define atomic number

A

The number of protons in an element (and the number of electrons because they are the same)

19
Q

Define mass number

A

The total number of protons and neutrons in an atom

20
Q

Define ion

A

Ions are charged particles formed when atoms, or groups of atoms, lose or gain electrons during chemical reactions

21
Q

What was John Dalton’s theory about the atom?

A

Atoms were solid spheres with nothing in them

22
Q

What was the plum pudding model and who invented it?

A

The plum pudding model described an atom that was a large positive mass with electrons embedded within it like a pudding cake with plums in it. It was invented by J.J. Thomson

23
Q

What was Rutherford’s experiment?

A

Rutherford fired positively charged alpha particles at a thin sheet of gold foil (atoms).

24
Q

What was the expected result of Rutherford’s experiment?

A

Rutherford expected all the particles to pass straight through as there was not enough strong positive charge to deflect any of them.

25
Q

What actually happened in Rutherford’s experiment?

A

A few of the alpha particles deflected or came straight back, leading to the nuclear model of the atom

26
Q

What was the nuclear model of the atom?

A

A nucleus of protons surrounded by a cloud of electrons

27
Q

What was Bohr’s model?

A

Bohr’s model had the electrons orbiting the atom in electron shells so that they would not get attracted to the positively charged nucleus

28
Q

What did James Chadwick discover?

A

He discovered neutrons and their place in the nucleus