Chemistry Flashcards
What are elements
substances that contain only one type of atom
what is a compound
substance made of more than one type of element chemically combined
what is a mixture
two or more elements or compounds not chemically combined
how do you separate an insoluble solid from a liquid
you filter it
crystallisation method
- add an impure solid to a solvent
- place the mixture in an evaporating basin
- until crystals start to appear
- leave the liquid to evaporate
- separate soluble solid from solvent to collect solid
when is fractional distillation used
to separate a mixture of liquids
distillation method
- heat the mixture
- evaporate the solvent
- pass vapours into the condenser
- collect the condensed liquid
- separate soluble solid from solvent to collect liquid
when is paper chromatography is used
used to separate a mixture of solids dissolved in a solvent
- solids with more attraction to solvent moves further up paper
what is the earliest idea of atoms
that atoms are the smallest particles which could not be divided
what is a plum-pudding model
a ball of positive charge with electrons embedded within
what is the nuclear model
- Made by Rutherford and Marsden
- positively charged nucleus surrounded by electrons
Alpha scattering experiment
- most alpha particles passed through atom
- those that hit centre were repelled
What did Bohr suggest?
electrons were in energy shells around nucleus
What did James Chadwick discover?
discovered the nucleus had positive protons and neutrons surrounded by electrons
what are ions
an atom that has gained or lost electrons
what is the atomic number and mass number
- atomic number : proton
-mass number : proton + neutron
how to calcutulate RAM
∑ isotope mass x isotope abundance / 100.
what is the charge of each subatomic particle
- proton : +1
- neutron : 0
- electron : -1
How did Dalton organise periodic table?
in order of atomic weight
what are isotopes
elements with the same proton number but different neutron number
Wat do elements in the same group have?
- same outer shell
- similar properties
what are the meanings of columns and rows?
- columns = groups
- rows = periods
What did Newland notice?
every eighth element was similar
What was Medeleev’s order?
- ordered atomic weight in rows
- elements with similar properties in same column
How is modern table organised?
-has atomic nu,mber in rows
- similar properties in same column
Formation of table
- metals on left
- non metals on right
What type of ions do they form?
- metals form + ions
- non metals form - ions
What are the properties for Group 0 elements?
- noble gases
- full outer shell
- boiling point increases as you go down
- unreactive
What are the properties of group 7 elements
- halogens
- mass, bpt, mpt gets higher as you go down
- less reactive as you go down
- more reactive halogens displaces less reactive from a solution of its salt
What is ionic bonding
- happens between metal and non-metal
- is an electrostatic force of attraction between oppositely charged ions
what are the properties of group 1 elements?
- alkali metals
- more reactive as you go down
- when reacts with water, metal hydroxide and hydrogen is produced
why do different particles have different mpt and bpt?
strength of the forces between the particles is responsible
- stronger forces = higher mpt and bpt
what are the properties of transition metals?
- have higher mpt, bpt
- more dense than group 1 metals
- less reactive than alkalis
- form ions of many charges
-compound are often coloured
-often used as catalysts
Topic 2