C1

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  • Created by: Shajitha
  • Created on: 16-02-18 17:07
What are Particles?
A particle is a tiny bit of matter. Particles can be large enough to see, like piece of dust, or too small to see, even with a microscope.
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What is the Particle Model?
The particle model describes how particles are arranged and how they move in solids, liquids, and gases. The particle model explains why some of the properties of a substance depends on its state.
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What are Physical changes?
A physical change happens when a substance changes state or shape, or breaks into pieces. No new substances are made. Many physical changes can be reversed, such as freezing juice to make ice lolly.
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What are Chemical changes?
A chemical change is a change that produces one or more new substances. The properties of the new substances are often very different from the properties of the original substances, such as cooking eggs and cakes.
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What happens to particles during changes?
When a substance changes state, its particles stay the same but their arrangement and movement change. In a chemical change, particles break up and then join together in different ways. This is why new substances are made.
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How big are particles?
The smallest particles that make up a substance are called atoms. Helium atoms are the smallest of all atoms it is so tiny that the diameter of a helium atom is about a billion times smaller than the diameter of a tennis ball.
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What is the equation of the space between an atom?
Ratio of distance to diameter = distance between atoms ÷ diameter of atom
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What are the forces between particles?
These are electrostatic forces of attratction between positive and negative charges. The forces become weaker the further apart the particles are. They are strongest in solids, and weakest in gases.
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What are the limitations of the particle model?
The particle model is helpful, but is not perfect. It does not take into account the forces between particles, the size of particles and the space between particles.
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What are Atoms and Molecules?
An atom is the smallest particle of an element that still has its chemical properties. Different elements are made from different atoms. A molecule is made from two or more atoms chemically bonded together.
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What is inside an Atom?
While the inside of an atom is mostly empty space, it does contain three even smaller subatomic particles, such as protons and neutrons, joined together as the nucleus at the centre and electrons, surrounding the nucleus in shells.
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What is the Atomic Number?
The bottom number is the atomic number for that atom. This is the number of protons in its nucleus. Every atom has equal numbers of protons and electrons, so the atomic number also tells us how many electrons it has.
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What is the Mass Number?
The top number is the element's mass number. This is the total n umber of protons and neutrons. You can use the mass number and atomic number to calculate the number of neutrons. Mass Number = Number of Protons (atomic number) + Number of Neutrons
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What are Isotopes?
Isotopes of an element are atoms with the same number of protons and electrons but different numbers of neutrons. This means that isotopes have the same atomic number, but their mass number is different.
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What are Ions?
Ions are cahrged particles. They are formed when atoms, or groups of atoms, lose or gain electrons. This can happen during chemical reactions, like the one between sodium and oxygen.
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What did Dalton do?
In 1803, John Dalton suggested that all matter is made from atoms. It also explained evidence from his experiments on gases such as all atoms of an element are identical and different elements contain different types of atom.
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What did Thomas do?
Thomas discovered the first subatomic particle, the electron, in 1897. In his plum-pudding model. Thomas suggested that atoms are spheres of positive charge with electrons dotted around inside, like pieces of fruit in a cake.
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What did Rutherford do?
Rutherford worked with Hans Geiger and Ernest Marsden. Rutherford explained the results by suggesting that an atom has a positively charged nucleus containing most of its mass. He also suggested that outside the nucleus, electrons orbit like planets.
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What did Bohr do?
Bohr realised that orbiting electrons would be attracted to the oppositely charged nucleus and would rapidly spiral inwards. Bohr showed that electrons occupy fixed energy levels, or shells, around the nucleus.
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Other cards in this set

Card 2

Front

What is the Particle Model?

Back

The particle model describes how particles are arranged and how they move in solids, liquids, and gases. The particle model explains why some of the properties of a substance depends on its state.

Card 3

Front

What are Physical changes?

Back

Preview of the front of card 3

Card 4

Front

What are Chemical changes?

Back

Preview of the front of card 4

Card 5

Front

What happens to particles during changes?

Back

Preview of the front of card 5
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