Atomic Structure And The Periodic Table Flashcards
Element
A substance made up of one type of atom
Compound
A substance made up of two or more different chemical elements combined
Separated into elements by chemical reactions
Mixture
A substance made up of two or more chemical elements that are not combined
Separated by separation techniques (filtration + chromatography)
Electron
Negatively charged subatomic particle
Relative charge = -1
Mass number = 0
Proton
Positively charged subatomic particle
Realtive charge = +1
Mass number = 1
Neutron
Neutral charged subatomic particle
Relative charge = 0
Mass number = 1
JJ Thompson
Plum pudding -
Atom consisted of positive “dough” with negative electrons
Ernest Rutherford
Gold foil experiment (nuclear model of the atom) -
Shoot alpha particles at a gold foil to see if they go through or bounce back, as a result, he discovered the nucleus
Niels Bohr
Electrons orbiting -
He discovered that electrons orbit the nucleus at a fixed distance
James Chadwick
Neutron -
He discovered the neutron
Mass number
Total number of protons and neutrons
Atomic number
The charge in the nucleus (number of protons)
Relative atomic mass
Average value that takes account of the abundance of the isotopes of the element
The modern periodic table
Ordered by increasing atomic number
Elements with similar properties are in groups
Mendeleev’s periodic table
Left gaps
Elements with similar chemical properties were together
Ordered by increasing atomic weight
Isotopes made it possible to explain why the order based on atomic weight was not always correct
Half equations
When ions gain or lose electrons
E.g. Na+ + e- → Na
2H+ + 2e- → H2
Ionic equations
Write the formula of all atoms and ions (atoms have no charge)
Write it as one big equation
Remove spectator ions
Properties of group 1 - alkali metals
Soft (can be cut with a knife)
Low melting points (decreases down the group)
Low densities
Reactivity increases down the group
Group 1 reactivity trends
Reactivity increases down the group:
As the atoms have greater shielding and are further away from the electron being lost
Properties of group 0 - noble gases
Low boiling points (increases down the group)
Unreactive
Attractive forces become stronger down the group as the atoms become larger and therefore the intermolecular forces are stronger
Group 7 - halogens
Melting and boiling points increase as you go down the group as the atoms become larger and therefore the intermolecular forces are stronger
Reacts with metals to produce salts
Displacement reactions
Group 7 reactivity trends
Reactivity decreases down the group as:
There is greater shielding and greater distance from the nucleus as you go down the periodic table
Transition metals
Good conductors of heat and electricity
Dense, strong, and shiny
Less reactive to H2O and O2
Higher melting points than group 1
Some are catalysts and form coloured compounds
Filtration
Used to separate an insoluble solid from a liquid
Place a filter funnel, with filter paper inside, over a beaker
Pour the solid and liquid into the filter funnel
The liquid is collected in the beaker, with the solid being caught in the filter paper
Evaporation - distillation
Used to separate a liquid from a solid
Heat up the mixture of the solid and liquid
Once the liquid evaporates it will enter the condensing column
The vaporised gas will turn back into a liquid
Crystallisation
Used to produce sold crystals from a solution
A solution is placed in an evaporating basin and heated with a Bunsen burner
The volume of the solution has decreased because some of the water has evaporated
Solid particles begin to form in the basin
All the water has evaporated, leaving solid crystals behind
Let the crystals air-dry
