Categorie: Tutti - bonding - elements - compounds - ions

da teo bernice mancano 17 anni

467

Molecules and Ions

bernice teo FS 0703

Molecules and Ions

Molecules and Ions

Forming Compounds

chemical compounds have constant composition.
formed when elements are chemically combined together in a chemical reaction.
Covalent compounds
Certain covalent compounds with special names

e.g. water, ammonia, methane

prefix is added to distinguish atoms

Penta- (5)

Tetra- (4)

Tri- (3)

Di- (2)

Mono- (1)

second element ends with "-ide"

e.g. hydrogen chloride

Ionic compounds
Polyatomic ions

e.g. nitrate, carbonate

Combining cation and anion

e.g. sodium chloride, where the overall charge is zero.

Negative ions(anions)

e.g. chloride ion

Positive ions(cation)

e.g. sodium ion

Ions
Ionic bonding

transfering of electrons from metal to non-metal atom

Molecules
covalent bonding

occurs between atoms of non-metals

Basic Constituent of matter

Periodic Table
Atomic mass
Symbol of element
Atomic number
Atomic Mass
Weighed average of masses of an element
Isotopes
Difference in number of neutrons
cannot be broken down e.g. carbon
in their simplest form
Atoms
Mass no. = no.of protons + no.of neutrons
No. of protons = No. of electrons
remain the chemical properties of element
smallest particle
Structure of atom

electrons

Relative charge is -1. (-1.6 x 10^-19 C)

Relative mass is 1/1830. (9.11 x 10^-31 Kg)

neutrons

Relative mass is 0. (0C)

Relative mass is 1. (1.67 x 10^-27 Kg)

protons

Relative charge is +1. (+1.6 x 10^-19 C)

Relative mass is 1.(1.67 x 10^-27 Kg)

Classification of matter

Particles
Can be separated by physical methods

distilling

sedimentation

filtering

evaporating

dissolving

Mixtures

Heterogeneous

e.g. salad,concrete

Homogeneous

e.g solutions,milk

Pure Substances

Compounds

atoms of different kinds e.g. water

Elements

atoms of the same kind e.g. oxygen