Basic Concepts About Matter

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