Chapter 1: Introduction: Matter and Measurement

Chapter 1: Introduction: Matter and Measurement

The Study of Chemistry

The Molecular Perspective of Chemistry

Matter – physical material of the universe, has mass and takes up space

Atoms – the building blocks of matter

Molecules – groups of combined atoms

Why Study Chemistry?

important in understanding our world
chemistry is the central science
many various subjects have some kind of relation to chemistry

Classification of Matter

States of Matter

states of matter: liquid, solid, and gas

Pure Substances and Mixtures

pure substance – matter that has a fixed composition and distinct properties
substances can be classified as elements or compounds

elements – composed of only one atom

compounds – two ore more elements

mixtures – combination of two or more substances

heterogeneous – mixtures that are not uniform throughout

homogeneous – mixtures that are uniform throughout; also called solutions

Separation of Mixtures

components in a mixture retain their own properties
mixtures can be separated by using the different properties of each substance
types of separation: filtration, distillation, chromatography

Elements

over 90% of earth’s crust consists of oxygen, silicon, aluminum, iron, and calcium
human body consists of 90% of oxygen, carbon, and hydrogen

Compounds

law of constant composition (law of definite proportions) – elemental composition of a pure compound is always the same

Properties of Matter

physical properties – properties measured by not changing the identity and composition of the substance

chemical properties – the way a substance may change or react to form other substances

intensive properties – identify substances

extensive properties – amount of substance

Physical and Chemical Changes

physical change results in a change in appearance but not composition
changes of state are physical changes
chemical changes (chemical reactions) results in a chemically different substance

Units of Measurements

SI Units

seven base units

Prefix

Abbreviation

Meaning

Mega-

M

10⁶

Kilo-

K

10³

Deci-

D

10^-1

Centi-

C

10^-2

Milli-

m

10^-3

Micro-

µ^a

10^-6

Nano-

n

10^-9

Pico-

p

10^-12

Femto-

f

10^-15

Length and Mass

SI base unit for length is the meter (m)
Mass is a measure of the amount of material in an object

Temperature

Celsius and Kelvin scales are used commonly in science
Both have equal sized units
K = °C + 273.15
°C = (5/9)(°F –32)
°F = (9/5)(°C) + 32

Derived SI Units

Volume

SI unit is cubic meter
Equipment to measure volume accurately : syringes, burets, and pipets

Density

density = mass/volume

Uncertainty in Measurement

1.5.1 Precision and Accuracy

precision – the closeness of individual measurements to one another

accuracy – the correctness of individual measurements

Significant Figures

Nonzero digits are always significant
Zeros between nonzero digits are always significant
Zeros at the beginning of a number are never significant
Zeros that fall both at the end of a number and after the decimal point are always significant
When a number ends in zeros but contains no decimal point, the zeros may or may not be significant
Scientific notation can be used to get the correct significant numbers

Significant Figures in Calculations

the number of significant figures is determined by the number that has the fewest significant figures in the calculation

Dimensional Analysis

aid in problem solving
conversion factor – fraction where the numerator and denominator are the same quantity

Prefix	Abbreviation	Meaning
Mega-	M	10⁶
Kilo-	K	10³
Deci-	D	10^-1
Centi-	C	10^-2
Milli-	m	10^-3
Micro-	µ^a	10^-6
Nano-	n	10^-9
Pico-	p	10^-12
Femto-	f	10^-15