C1 Flashcards
What is a particle?
A particle is a tiny bit of matter
What are physical changes?
Physical changes are when a substance changes state or shape, or breaks into pieces. No new substances are made.
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 to the properties of the original substances.
What’s the average size of an atom
1x10^-10
What is a molecule?
A molecule is made from two or more atoms joined together. They are joined by attractive forces called chemical bonds.
What is the particle model?
The particle model describes how particles are arranged and how they move in solids,liquids and gases.
What is an atom?
The smallest particle of an element that still has its chemical properties
What is a molecule?
A molecule is the smallest particle made from two or more atoms joined together. They are joined by attractive forces called chemical bonds.
What is inside an atom?
It contains three subatomic particles
-protons
-neutrons
-electrons
Protons
Relative mass: 1
Relative charge: +1
Neutron
Relative mass: 1
Relative charge: 0
Electron
Relative mass: 0.0005
Relative charge: -1
What does the atomic number show?
How many protons are in an elements nucleus.
What does the mass number show?
The total number of protons and neutrons
What are isotopes?
Isotopes of an element are atoms with the same number of protons and electrons but a different number of neutrons.
What are ions?
Ions are charged particles. They are formed when atoms, or groups of atoms, lose or gain electrons. This can happen during chemical reactions.
How do you calculate the ratio of distance to diameter?
Ratio of distance to diameter =distance between atoms/diameter of atom
What are the forces between particles?
Electrostatic forces of attraction between positive and negative charges.
(Strongest in solids, weakest in gases)
What are limitations of the particle model?
Doesn’t take into account:
-The forces between particles
-The size of particles
-The space between particles
What did dalton do?
Dalton suggested that atoms are smaller balls.
- all atoms of an element are identical
- different elements contain different types of atoms
What did Thompson do?
Thompson discovered electrons.
-atoms are neutral overall
-atoms contain electrons
Plum pudding model
What did Rutherford do?
Suggested that atoms have a positively charged nucleus containing most of its mass
-electrons orbit like planets in a solar system
What did Bohr do?
Suggested that orbiting electrons are attracted to the oppositely charged nucleus and would rapidly spiral inwards.
-electrons occupy fixed energy levels, shells around the nucleus
