atomic structure & periodic table Flashcards
all substances are made of…
atoms
atom=
smallest part of element
element=
substance that contains 1 sort of atom
compounds=
- contain atoms of of 2 or more elements
- can only be separated into their component elements by chemical reactions or electrolysis
reactants:
substances that react (left side)
products:
new substances formed (right side)
mixtures
consists of two or more elements or compounds which are not chemically combined
how can mixtures be separated?
physical processes
filtration
separate soluble solid from a solution
salt + sand
cut
obtain soluble solid from a solution
salt from salt water- heated then evaporated
simple distillation
obtain solvent from solution
fractional distillation
separate mixtures with components with different boiling points
chromatography
separate the different soluble coloured components of a mixture
proton
relative mass: 1
relative charge: +1
neutron
relative mass: 1
relative charge: 0
electron
relative mass: very small
relative charge: -1
number of nutrons =
mass number - atomic number
atoms have…
no overall charge
contain equal n of protons + electrons
isotopes
-same n of protons
-different n of nutritions
(sane atomic n but different mass n)
ions
atom that gain or lose electrons
metal atoms lose electrons to
form positive ions
non-metal atoms gain electrons to
form negative ions
first shell:
can hold max 2 electrons
next two shells:
hold max 8 electrons
group 0
- noble gases
- full outer shell
- unreactive non-metals
group 1
- alkali metals
- one electron in outer shell
- low melting & boiling point
- become more reactive down the group
- low density
group 7
- non metal
- halogens
- 7 in outer shell
- reactivity decreases down group