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, all have three significant digits

Sig Fig - Rule 2 Zeros appearing between nonzero digits are significant Example: has 5 Sig Figs 5.07 has 3 Sig Figs as 6 Sig Figs

Rule 3 – Sig Figs Zeros in front of all nonzero digits are not significant Example: , 0.479, ,

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: 4.90x10 3.

Sig Figs? x

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 (m 3 ) 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 1/299,792,458 th 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 cm 3 = 1 L

Mass 1 kilogram is defined by a weight in France roughly equal to the mass of 1 L of water at 4 0 C.

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 = 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 kK in dK 5 x ns in das.

Multistep Problems How many seconds in one year? How many milligrams of water in 0.45 liters?