Atomic Structure & The Periodic Table
What is an atom?
The smallest part of an element that can exist.
What is Dalton's model of the atom?
Atom as a solid sphere that could not be divided into smaller parts.
What is the plum pudding model of the atom?
A sphere of positive charge with negative electrons embedded in it.
What did scientists discover in the alpha scattering experiment?
Some alpha particles were deflected by the gold foil - this showed that an atom's mass and positive charge must be concentrated in one small space (the nucleus).
What is the nuclear model of the atom?
An atom that nearly all of its mass is concentrated in a dense, positively charged nucleus at the center, with electrons orbiting around it.
What did Niels Bohr discover?
Electrons orbit in fixed energy levels (shells).
What did James Chadwick discover?
Uncharged particle called the neutron.
Where are protons and neutrons?
In the nucleus.
What is the relative mass of each subatomic particle?
proton: 1, neutron: 1, electron: 0
What is the relative charge of each subatomic particle?
proton: +1, neutron: 0, electron:-1
How can you find out the number of protons in an atom?
By looking at the atomic number on the Periodic Table.
How can you calculate the number of neutrons in an atom?
Mass number - atomic number.
Why do atoms have no overall charge?
Atoms have an equal number of positive protons and negative electrons.
How many electrons would you place in the first, second, and third shells?
first: 2, second: 8, third: 8
What is an element?
A substance made of one type of atom.
What is a compound?
A substance made of more than one type of atom chemically joined together.
What is a mixture?
Two or more substances not chemically combined.
What are isotopes?
Atoms of the same element (same number of protons) with different numbers of neutrons.
What is relative mass?
The average mass of all the atoms of an element.
What are the four physical processes that can be used to separate mixtures?
Filtration, crystallisation, distillation/fractional distillation, chromatography.
How is the modern Periodic Table ordered?
By atomic number.
How were the early lists of elements ordered?
By atomic mass.
Why did Mendeleev swap the order of some elements?
To group them by their chemical properties.
Why did Mendeleev leave gaps in his Periodic Table?
Leave room for elements that had not yet been discovered.
Why do elements in a group have similar chemical properties?
Have the same number of electrons in their outer shell.
Where are metals and non-metals located on the Periodic Table?
Metals to the left and non-metals to the right.
What name is given to the Group 1 elements?
Alkali.
What name is given to the Group 7 elements?
Halogens.
What name is given to the Group 0 elements?
Noble gases.
Why are the noble gases inert?
They have full outer shells so do not need to lose or gain electrons.