Chemistry• Chemistry – the study of the composition of

substances and the changes that substances undergo.

Branches of Chem.• Organic Chem.

• Inorganic Chem.

• Analytical Chem.

• Physical Chem.

• Biochemistry

• Theoretical

Building Blocks of Matter

• Atom – the smallest unit of an element that maintains the properties of the element

• Element – pure substance made of only one kind of atom

• Compound – substance made from atoms of two or more elements.

Properties of Matter

• Extensive Properties – depends on the amount of matter present (i.e. volume)

• Intensive Properties – Do not depend on the amount of matter present (i.e. boiling point)

Matter• Matter – anything that takes up space and

has mass

• Mass – that amount of matter that an object contains

Changes in Matter• Physical Change –

alteration of a substance without changing it’s composition

• Chemical Change – alteration in the chemical makeup of a substance

States of Matter• Solids – matter that has definite shape and

volume

• Liquids – matter that has definite volume, but takes the shape of its container

• Gas – matter that takes both the shape and the volume of its container

Mixtures• Heterogeneous Mixture

• Homogeneous Mixture

• Solution – a homogeneous mixture

• Phase – any part of a system with uniform composition and properties

Periodic Table• The known elements are organized on the

periodic table.

• Vertical columns are called groups or families

• Horizontal rows are called periods.

Measurements

• Quantitative – Results in a definite forms (usually as numbers)

• Qualitative – Results in a descriptive nonnumeric form

Accuracy and Precision

• Accuracy – How close a measurement comes to the actual true value of what is measured

• Precision – How well a measurement can be reproduced

Significant Figures

• Significant Figures – measurement that includes all digits that can be known accurately plus a last digit that is estimated

Rule One of Significant Figures

• 1) Every nonzero digit in a recorded measurement is significant

• Example: 56.8, 967, 0.735 all have three significant digits

Sig Fig - Rule 2

• Zeros appearing between nonzero digits are significant

• Example: 40005 has 5 Sig Figs

• 5.07 has 3 Sig Figs

• 20.9804 as 6 Sig Figs

Rule 3 – Sig Figs

• Zeros in front of all nonzero digits are not significant

• Example: 0.9837, 0.479, 0.00000084, 0.0000478

Rule 4 – Sig Figs

• Zeros at the end of a number and to the right of a decimal point are significant

• Example: 76.00, 5.080, 4.000

Rule 5 – Sig Figs

• Zeros at the end of a measurement and to the left of a decimal point can be either significant or not depending on how it was measured.

• Example: 300, 2900, 510.• To avoid the unknown, measurements

should be written in scientific notation: 4.90x103.

Sig Figs?

• 145

• 0.274

• 40.308

• 9.700 x 103

• 5.700

• 0.089

• 0.0707

• 76.00

Metric System• Metric System – the standard of

measurement used by scientists

• Established in 1790, the International System of Units (SI units)

SI Units• Length• Meter (m)• Volume• Cubic meter (m3) • Mass• Kilogram (kg)• Temperature• kelvin (K)

• Time• Seconds (s)• Pressure• Pascals (pa)• Energy• Joule (J)

Length• Meter – the distance that light travels in a

vacuum in 1/299,792,458th of a second.

Volume

• Liter – volume of a cube that is 10 m on each edge.

• 10 cm x 10 cm x 10 cm =1000 cm3 = 1 L

Mass• 1 kilogram is defined by a weight in France

roughly equal to the mass of 1 L of water at 40C.

Density• Density – the ratio of the mass of an object

to its volume

• Density = Mass / Volume

• Density is a derived unit because it is a combination of SI base units

Problem Solving

• Problem is a necessary part of chemistry and can only be mastered by practice.

Techniques for Problem Solving

• Identify the unknown• Identify what is given• Plan the solution• Do the calculations• Check your work

Sample Problem

• How many dimes is the equivalent to 10 quarters?

Conversion Factors

• Conversion Factors are ratios of equivalent measurements

• 1 foot = 12 inches

• 1 foot / 12 inches = 1

• 2.54 cm = 1 inch

• 1 inch / 2.54 cm = 1

Dimensional Analysis

• Dimensional Analysis – when units that are part of a measurement are used to solve a problem

• Usually this involves the use of conversion factors

Sample

• A recipe for cookies requires: 3 eggs, 2 cups flour, 1 cup sugar to make 3 dozen cookies

• If you wanted to make enough cookies for exactly 144 people, how many cups of flour do you need?

• How many eggs do you need for 12 people?

Converting Between Units

• 3000 mm in meters

• 0.000005 kK in dK• 5 x 1010 ns in das.

Multistep Problems

• How many seconds in one year?

• How many milligrams of water in 0.45 liters?