Atomic Structure and The Periodic Table Flashcards
Who discovered neutrons
Chadwick
Who discovered electrons
Thompson
Who discovered protons
A series of experiments
Who discovered electron shells
Bohr
Who discovered the nucleus
Rutherford
What did Rutherford discover
nucleus
Who conducted the gold foil experiment
Rutherford
What order was each part of the atom discovered in
1) electrons (Thompson plum pudding model)
2) nucleus (Rutherford nuclear model)
3) electron shells (Bohr)
4) proton (series of experiments)
5) neutron (Chadwick)
What model did Rutherford create of the atom
Nuclear model (atom mostly empty space with electrons orbiting the positive nucleus)
(Electrons had already been discovered so they had to go somewhere in his model but not embedded as he found the atom was mostly empty space so he decided they would orbit around the edge- Bohr then finds that they orbit at set distances)
What model did Thompson create of the atom
Plum pudding
Positively charged atom with negative electrons embedded in it
True or false, in the nuclear model the electrons orbit the nucleus
True, but not at set distances as Bohr later discovers
What was concluded from the gold foil experiment and why
Atom is mostly empty space (most alpha particles went straight through)
Concentrated mass in centre of atom (some alpha particles deflected)
Concentrated mass is positive (some alpha particles reflected)
What is the radius of an atom in metres
1x10 ^-10m
What is the radius of a nucleus in metres
1x10^-14m
4 ways to separate mixtures
Chromotatography
Distillation (fractional and simple)
Crystallisation
Filtration
Properties of group 0 elements (Noble gases)
Unreactive due to full outer shell of electrons so they are stable (don’t need to lose or gain any electrons)
Exist as single atoms (are unreactive so don’t bond to form molecules)
Low melting/ boiling point
Boiling points increase down group
How does the boiling point change going down group 0 (Noble gases)
Increases
What is the name for group 1 metals
Alkali metals (react with water to form an alkali)
Why are group 1 elements very reactive
Have 1 electron in outer shell so it is easy to lose just this 1 outer electron and react
Does reactivity increase or decrease going down group 1 and why
Increase
- atom increases in size (larger radius)
- outer electron further away from nucleus
- more shells shielding outer electron from nucleus
- weaker electrostatic forces acting between negative outer electron and positive nucleus
What happens to boiling point going down group 1
Decreases
What happens to boiling point going down group 7 (halogens)
Increases
What happens to reactivity going down group 7
Decreases
Why does reactivity decrease going down group 7 (but increases going down group 1)
More electron shells so more shielding between nucleus and outer electrons
Weaker electrostatic forces acting between nucleus and outer electrons so harder for an electron to be attracted to the nucleus and to be gained on the outer shell
(In group 7 the atom is trying to gain an electron so further away the electrostatic forces are weaker so there is less attraction meaning it is harder to gain the electron. But in group 1 if further away the electrostatic forces are weaker this means that the outer electron is less attracted to the nucleus so can be more easily lost)
Difference between how reactivity changes going down group 1 and group 7
Group 1- increases
Group 7- decreases
What do group 1 elements form when they react with water
Metal hydroxide + hydrogen
What do all halogens exist as
Diatomic molecules
(Pairs of atoms chemically bonded together)
When 3 or more elements combine with 1 being oxygen what does it end in
Ate
Physical properties of alkali metals
Soft
Relatively low melting points
Low densities
Chemical properties of alkali metals
Highly reactive
Reactive with water to form metal hydroxides (alkalis)
True or false, group 7 elements get darker as you go down the group
True
How did John Newlands initially arrange known elements
Order of increasing atomic weight
‘Law of Octaves’ as elements with similar properties repeated every 8 elements
Problem: some elements were grouped together with completely different properties
How is the modern periodic table arranged
Increasing atomic number
Columns (groups)- all elements in same group have similar chemical properties (react in a similar way due to all having the same number of electrons in their outer shell)
How did Mendeleev develop the first modern periodic table
Increasing atomic weight
Left gaps for elements yet to be discovered which he predicted the properties of
He swapped some elements around
Physical Properties of transition metals
High density
High melting point
Hard
Strong
Good conductors of heat and electricity
Shiny
Are alkali metals (group 1) hard or soft
Soft
How many times smaller is the nucleus of the atom than the radius
10,000
4 differences between physical properties of elements in group 1 and transition metals
Group 1 have lower melting and boiling points, lower densities, are less strong and are softer
Further away from the nucleus is there more or less shielding
More (means electrostatic forces between outer electron and nucleus are weaker)
Is boiling point chemical or physical property
Physical
Fractional vs simple distillation
Fractional distillation separates multiple liquids from a solution based on boiling point (substances with similar boiling point)
Simple distillation separates a single liquid from a solution (substances with completely different boiling points) (the solution is heated, evaporated and condensed)
What is a compound
2 or more different elements chemically bonded together
Does a compound have to be 2 or more different elements
Yes
What is a molecule
2 or more atoms chemically bonded together (can be the same type)
What is a mixture
Contains 2 or more different substances not chemically joined
Why Mendeleev reverse the order of some pairs of elements
So their properties matched the rest of the group
4 differences between nuclear model and plum pudding model
Nuclear model has nucleus, plum pudding model does not
Nuclear model mostly empty space, plum pudding model is solid
Nuclear model positive charge is all in nucleus, plum pudding model atom has overall positive charge
Nuclear model electrons orbit nucleus, plum pudding model electrons are embedded into atom
Physical property of noble gases (group 0)
Low melting point
Why does boiling point increase going down group 0 (noble gases)
Atoms become larger
Intermolecular forces between atoms become stronger
More energy needed to overcome these forces
Chemical properties of group 0 (noble gases)
Un reactive) Full outer shell of electrons)
