notes

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Matter = Physical material of the Universe - anything that has mass and occupies space

Property = Any characteristic that allows us to recognise and distinguish one type of matter from another

Macroscopic = (macro = large)

submicroscopic = atoms + elements

atom = Smallest particle of

an element that

can exist

and still have the

properties of that element.

molecules = group of two or more atoms which function as a unit because the atoms are tightly bounded together

composition = types of atoms the matter contains

structure = arrangements of these atoms

solid = definite shape and definite volume

liquid = indefinite shape and definite volume

gas = indefinite shape and indefinite volume

physical properties = the composition of a substance does not change

chemical properties = the composition of a substance does change

most forms of matter we encounter are not chemically pure

can be resolved into different pure substances

pure substance is matter with distinct properties and a composition that does not vary from sample to sample

elements = cannot be decomposed into smaller substances

compounds are composed of two or more different elements

combinations of two or more substances in which each substance retains it's own chemical identity

these substances can be separated from the mixture into individual pure substances

heterogenous mixtures = mixtures whose composition can vary within a sample

homogenous mixtures = mixtures whose composition is uniform throughout a sample

we can separate components of mixtures by taking advantage of each individual substances properties

Elements

cannot be broken down into simpler substances by physical or chemical means

building blocks for all other types of matter

118 elements known

pure substance

one substance present

definite and constant composition

properties always the same under constant conditions

Compounds

can be broken down into constituent elements by chemical, but NOT physical processes

chemical combination of two or more elements

definite, constant elemental composition

Homogenous mixtures

one visible phase

same properties throughout

Mixture

Physical combination of two or more different substances

composition can vary

properties can vary with composition

Heterogenous mixtures

two or more visible phases

different properties in different phases

chemical symbols represent the elements

homoatomics - all atoms are the same kind

heteroatomics - two or more kinds of atoms present

chemical formulas provide the composition of a compound

made up of the symbols of the elements present in the compound and the numerical subscripts

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Summary

Chemistry studies the properties, composition and transformation of matter, also concerned with energy (heat, light, electricity)

Matter exists in three physical states: solid, liquid and gas

Physical

and chemical properties can be used in the

identification and description of a substance

Pure

substances (one substance) can be elements

and compounds.

Mixtures

(more than one substance) can be homogeneous or

heterogeneous

Chemical

symbols

(one- or two- letters) represent elements

An atom is

the smallest particle of an element that can exist and still have the

properties of an element. A molecule is

a group of atoms tightly bound together, which behave as a single

unit.

Molecules can be di, tri or polyatomic. Also homo or heteroatomic

Chemical

formulas

provide the composition of compounds