The Atom Flashcards
What did the Dalton (first) model of the atom look like?
A solid sphere that could not be split. It did not include protons, neutrons or electrons.
What did the plum pudding model look like?
Electrons in a cloud of positive charge.
The discovery of what led to Thomson’s plum pudding model?
Electrons
What happened in the alpha scattering experiment?
- Small, positively-charged (alpha) particles fired at gold foil
- Most particles travelled through it, while some bounced back or were deflected.
What did the alpha scattering experiment show?
That there must be a positively-charged mass concentrated at the centre of an atom -> nucleus.
What atomic model did the alpha scattering experiment lead to?
The nuclear model
What did the nuclear model look like?
A positively-charged centre of mass (nucleus) with electrons orbiting, but not at fixed distances.
What did the Bohr model show?
It is the same as the nuclear model, but the electrons orbit the nucleus at fixed distances (called shells or energy levels)
What is the difference between the Nuclear and Bohr models?
Nuclear - electrons orbit nucleus, but not at fixed distances
Bohr - electrons orbit nucleus at fixed distances
What was discovered after the Bohr model?
Protons
What did James Chadwick discover?
The neutron
What subatomic particles are in the nucleus?
Protons and neutrons
What is relative mass?
The masses of protons, neutrons and electrons compared to each other.
What is the relative mass of a proton?
1
What is the relative mass of a neutron?
1
What is the relative mass of an electron?
0
What is the size of an atom?
1 x 10^-10m
What is the relative charge of a neutron?
0
What is the relative charge of a proton?
+1
What is the relative charge of an electron?
-1
What is equal in subatomic particles?
The total negative charge from electrons and the total positive charge from protons
How do you work out the number of neutrons in an element?
Mass number - atomic number
How do you work out the number of protons in an element?
Atomic number
How do you work out the number of electrons in an element?
Number of electrons = number of protons
How many electrons can go in the first shell?
2
How many electrons can go in the other shells? (after the first)
8
What is a compound?
A substance made of different types of atoms chemically bonded together.
What will be different in a compound?
The number of protons
What will be the same in an element?
The number of protons
What is an isotope?
Atoms of the same element with different numbers of neutrons
What is relative atomic mass?
The average mass of all atoms of an element
What is abundance?
The percentage of atoms with a certain mass
How do you work out relative atomic mass?
(Abundance of isotope 1 x mass of isotope 1) + (abundance of isotope 2 x mass of isotope 2) all divided by 100
What is a mixture?
Two or more elements or compounds that are not chemically bonded
How can substances in a mixture be separated?
Physical processes - e.g: filtration, crystallisation, simple distillation…
What does filtration separate?
Insoluble solids from a liquid
What does crystallisation separate?
Soluble solid from a solution
What does simple distillation separate?
Solvent from a solution
What does fractional distillation separate?
Two liquids with similar boiling points
What does paper chromatography identify?
The substances from a mixture in a solution
How do you find the number of protons in an atom?
The atomic number on the Periodic Table
