Basic Concepts About Matter
Chemistry and Matter
Matter - anything that has mass and takes up space (has volume)
What are some examples?
Chemistry – the study of matter and the changes it undergoes
What types of chemists are there?
Three phases (states) of matter
What are the three phases of matter?
How do they compare in terms of shape, volume, and compressibility?
Physical and Chemical Properties
Physical property – can be observed without changing the identity of the substance
What are some examples?
Chemical property – describes how a substance undergoes (or resists) change (chemically reacts) to form new substances
What are some examples?
Physical and chemical changes
Physical change – substance changes in appearance but its identity is not changed
What are some examples?
Chemical change – substance changes (chemically reacts) in a way that changes its chemical composition and therefore changes its identity
What are some examples?
Properties and Changes
Pure substances and mixtures
Pure substance – can not be separated into simpler substances by physical means (as opposed to chemical reactions that break chemical “bonds”)
Mixture – two or more pure substances mingled in a way where each retains its own identity
Pure substances
Element: Pure substance that cannot be broken down into simpler substances by chemical means (breaking bonds) 115 known
Compound: Pure substance made up of two or more elements chemically combined. Can be broken down into those elements by chemical means. 9 million known
Mixtures
Homogeneous: Has one visible phaseHas the same composition throughoutExamples?
Heterogeneous:Has two or more visible phasesHas a different composition when sampled in different areasExamples?
Relative abundance of elements
Common elements and polyatomic ions The first three periods Family IA (the first six elements) Family IIA (the first five elements) Family VIIA (the first five elements) The following elements: Cr, Mn, Fe, Co, Ni, Cu, Zn,
Ag, Sn, Au, Pb, Hg
Know the following polyatomic ions: NH4+
(ammonium ion), OH- (hydroxide ion), NO3- (nitrate
ion), NO2- (nitrite ion), SO3
2- (sulfite ion), SO42-
(sulfate ion), PO43- (phosphate ion), CO3
2- (carbonate ion), HCO3
- (bicarbonate ion)
Atoms, molecules and compounds
Atom: smallest particle of an element that still has the properties of that element
Molecule: two or more atoms chemically combined
Compound: two or more atoms from different elements that are chemically combined
Different types of
molecules
Classify these as:a) diatomic, triatomic, etc…b) homoatomic or heteroatomicc) elemental or compound
Chemical formulae
Tells you what elements are present in a molecule and the number of atoms of each type of element
Molecular formula: Tells you the elements and the actual number of each atom within the true molecule
Empirical formula: Tells you the elements and the lowest whole number ratio of each type of atom