atomic structure and the periodic table

atom

the smallest particle of a chemical element

size of an atom

1 x 10^-10 m

compound

two or more different elements chemically bonded together

mixture

two or more elements or compounds that are not chemically bonded together

element

pure substance made of only one kind of atom

filtration

used to separate an insoluble solid from a liquid

solute

solid that dissolves

solvent

liquid in which something dissolves

solution

a solute dissolved in a solvent

distillation

used to separate substances with different boiling points

pure substance

a single element or compound

formulation

a mixture that has been designed as a useful product

chromotography

method used to separate mixtures and identify the substances

Rf value

the ratio of the distance moved by the compound compared tot the solvent

Rf value equation

Rf = distance travelled by substance / distance travelled by solvent

number on top of symbol

atomic mass

number below symbol

atomic number (=number of protons =number of electrons)

conservation of mass

the mass before the reaction is the same as the mass after

mendeleev & periodic table

created the first periodic table, ordered them by increasing atomic mass, left gaps for elements that he thought had not been discovered as they didn't fit the pattern

noble gases

group 0, low boiling point, unreactive, gas at room temp (helium & neon)

alkali metals

group 1, low density, react with water releasing hydrogen, react with oxygen to form oxides, more reactive as you go down, 1 electron on the outer shell (lithium & sodium)

group 1 + water

-> alkali + hydrogen

transition metals

higher melting points, stronger and harder, less reactive with oxygen, water and halogen

halogens

group 7, diatomic, less reactive as you go down, boiling point increases as you go down, called a halide when it reacts

displacement reaction

more reactive elements displace less reactive elements

diatomic

elements that exist as a pair of atoms