Chemistry Chapter 1 - Exam 1

What is Chemistry?

Study of matter and how it changes

Why is Chemistry important to learn?

Offers another layer of insight into natural systems

How do we do Chemistry?

Scientific approach to knowledge

Scientific approach to knowledge - Observations

Based on senses and/or recorded with an instrument

Scientific approach - Hypothesis

tentative explanation or interpretation of the observations

Scientific knowledge - Test

Verify hypothesis through experimentation

Scientific Law

A brief statement summarizing past observations and predicting future ones - Describes WHAT happens

Scientific Theory

A model for the way nature is, and tries to explain what nature does and why it does it - Explains WHY it happens

Matter

Anything that occupies space and has mass

What is Chemistry based on?

The atomic theory which states that all matter is composed of tiny particles called atoms and molecules

Solid

Fixed volume and rigid shape, not compressable

Liquid

Fixed volume, but not fixed shape and is not compressable

Gas

No fixed volume, no fixed shape, and is compressable

Macroscopic level

Observations like water boiling and vapor

Submicroscopic level

Atoms interacting and behaving

Symbolic Level

Example: H2O(l) = H2O(g)

Pure Substance

Fixed composition and unique set of properties. Cannot be separated into other substances by physical means

Mixture

A combination of two or more substances that are not chemically bonded and can be separated by physical mean

Compound

Pure substance - two or more types of atoms that are chemically bonded. Can be broken down only by chemical means: H2O, CO2

Element

Pure Substance - only one type of atom. Cannot be broken down into simpler substances: He, O2, H2

Heterogenous Mixture

Mixture - not uniform and has different parts with different properties: olive oil and water mix, cereal

Homogenoous Mixture

Mixture - uniform throughout and has the same composition and properties everywhere: tea, air, urine

Chemical Change

Alters composition of atoms or molecules

Physical Change

Atoms or molecules do not change their identity during physical change

Chemical Property

Property that a substance displays only by changing its composition via a chemical change

Physical Property

Property that a substance displays without changing its composition

Energy

Capacity to do work

Work

action of a force through a distance

Total energy

= Kinetic energy + Potential energy

Law of Conservation of Energy

Energy cannot be created or destroyed, only converted from one for to another

What kind of energy is Chemical energy?

Potential energy

SI Length

Meter (m)

SI Mass

Kilogram (kg)

SI Time

Second (s)

SI Temperature

Kelvin (k)

SI Amount of Substance

Mole (mol)

SI Electric Current

Ampere (A)

SI Luminous Intensity

Candela (cd)

SI

Internation System of Units

1 Kg

~2.2 lbs

1 g

1/1000 of a kg

1 m

1.09361 yds/39.37 in/3.28084 ft

1 millisecond (ms)

1/1,000 of a second

1 microsecond

1/1,000,000 of a second

Temperature is a measure of…

the average kinetic energy

Fahrenheit to Celsius

= (F-32)* 5/9

Celsius to Fahrenheit

= 9(C) + 52

Celsius to Kelvin

= C + 273.15

Boiling point

212 degrees F/ 100 degrees C/ 373 degrees K

Freezing Point

32 degrees F/ 0 degrees C/ 273 degrees K

Absolute zero

0 K

Derived units

Combination of other units

Volume

Space = length x width x height

Density

How much is packed into a certain amount of space

Density equation

mass/volume

Density changes with Temp

hotter = lower density, cooler = higher density

When converting between “powers,”

raise everything to that “power”

Random error

cause imprecision - inconsistent trial-to-trial measurements

Systematic error

cause measurements to be consistently off from true value in the same direction

Significant Figures (SF) Multiplication/Division

Count sig figs (total digits), round to smallest number of sig figs

Significant Figures (SF) Addition/Subtraction

Count decimal places, round to the smallest # of decimal places

Significant Figures (SF) Mixed operations

step-by-step apply the rules at each step and only round at the end of each step.