Unit 1 CHE 105

What do scientists do?

Ask questions, design experiments, gather & analyze data, make claims, and develop explanations

Scientific Method includes:

Observations, hypothesis, and experimentation

What is a hypothesis?

Initial explanation from observations or provided evidence; testable

What is a Theory?

Explains the phenoma (why/how it happens)

What is a Scientific Law?

Describes the phenomena; statements (what happens0

What is the Law of Conservation of Mass?

any chemical reaction or physical change that occurs will result in a mass that is equivalent to the mass before the change

Who discovered the Law of Conservation of Mass?

Antoine Lavoisier

What is a molecule?

2 or more atoms (same or different atoms)

What is a Compound?

2 or more types of elements (must have different atoms)

What is Matter?

anything that has mass and occupies space

What are all of the forms of matter?

solids, liquids, gas, and plasma

What is an element?

Simplest form of matter that has distinct phyical and chemical properties

Elements can be broken down into simpler substances (T/F)

false

What are elements collections of?

Atoms

Do elements contain only one type of atoms? (Y/N)

Yes

What is an Atom?

smallest identifiable unit of an element

What is a molecule?

Two or more atoms joined in a specific arrangement of chemical bonds

All compounds are molecules but all molecules are not compounds (T/F)

True.

Substance

A form of matter that has a definite composition and distinct properties

Examples of substances?

Salt, iron, water, mercury, carbon dioxide, and oxygen

What is a mixture?

A physical combination of two or more substances

What is a homogeneous mixture?

Uniform composition throughout; solution

What is a heterogeneous mixture?

Not uniform throughout

Examples of a homogeneous mixture

Seawater, apple juice

Examples of a heterogenous mixture

Trail mix, chicken noodle soup

Is every compound a true substance? (Y/N)

Yes

Every mixture contains two or more compounds (T/F)

False

Every compound contains two or more elements (T/F)

True

Every pure substance is a compound (T/F)

False

What are properties of matter?

Characteristics that can distinguish one substance from another

What are physical properties?

Properties that don’t change atomic or molecular composition

Examples of physical properties

Odor, taste, color, appearance, melting point, boiling point, and density

What are chemical properties?

Properties that DO change in atomic and/or molecular composition

Examples of chemical properties

Corrosiveness, flammability, acidity, and toxicity

What are Extensive Properties?

Properties dependent on the AMOUNT of matter

Examples of extensive properties

Mass, volume, length, and weight

What are intensive properties?

Properties not dependent on the amount of matter

Examples of intensive properties

Temperature, density, boiling point, melting point, magnetism, and color

What are properties of compounds?

Constant and typically diffewrent from the properties of the elements inside of them

What are the properties of mixtures?

Similiar to the properties of the parts of the mixture, but can change depending on the amount of each part in the mixture

What is a physical change?

Where the state changes but the identity does not

Examples of a physical change

Melting, freezing, condensation

What is a chemical change?

Where the composition changes and the original substance no longer exists

Examples of a chemical change

Digestion, combustion, and oxidation

What is the starting material in a chemical change?

Reactant

What is the resulting material in a chemical change?

Product

What happens in a chemical change?

Chemical bonds are formed/broken

What happens when bonds are broken?

Energy is absorbed from the surroundings

What happens when bonds are formed?

Energy is released into the surroundings

What is the mass of an object?

How much matter is measured within the object

What is the Law of Conservation of Energy?

Energy cannot be created or destroyed but can be converted from one form to another

What are examples of different forms of energy?

Heat, chemical, nuclear, mechanical, electrical, sound, and electromagnetic radiation (HCNMESE)

What is density?

A measure of how much mass something has that is relative to how much space it takes up

Objects that are less dense do not float in fluids that are denser (T/F)

False; objects that are less dense float in fluids that are denser

Equation for density?

Density is mass per unit volume, so; density = mass/volume

What are the three different temperature scales?

Fahrenheit, celsius, and Kelvin

Fahrenheight freezing point

32 Degrees fahrenheit

Fahrenheit boiling point

212 degrees fahrenheit

Celsius freezing point

0 degrees celsius

Celsius boiling point

100 degrees celsius

Kelvin boiling point

373.15 K

kelvin freezing point

273.15 K

What are quantitative properties?

Properties that can be measured

Examples of the english system

Foot, gallon, pounds

Examples of the metric system

Meter, liter, kilograms

Examples of SI base units

Length, mass, time, electric current, temperature, amount, and luminous intensity

Length (SI Base Unit)

Meter; m

Mass (SI Base Unit)

Kilogram; kg

Time (SI Base Unit)

Second; s

Electric Current (SI Base Unit)

Ampere; A

Temperature (SI Base Unit)

Kelvin; K

Amount (SI Base Unit)

Mole; mol

Luminous Intensity (SI Base Unit)

Candela; cd

tera- (T) (SI Prefix)

10¹²

giga- (G) (SI Prefix)

10⁹

mega- (M) (SI Prefix)

10⁶

kilo- (k) (SI Prefix)

10³

deci- (d) (SI Prefix)

10^-1

centi- (c) (SI Prefix)

10^-2

milli- (m) (SI Prefix)

10^-3

micro- (μ) (SI Prefix)

10^-6

nano- (n) (SI Prefix)

10^-9

pico- (p) (SI Prefix)

10^-12

femto- (f) (SI Prefix)

10^-15

atto- (a) (SI Prefix)

10^-18

Volume (SI Derived Unit)

m³

Speed (SI Derived Unit)

m/s

Acceleration (SI Derived Unit)

m/s²

Density (SI Derived Unit)

kg/m³

Frequency (SI Derived Unit)

Hertz ; s^-1

Force (SI Derived Unit)

N ; kg * m/s²

What is a conversion factor?

a fraction where the same quantity is expressed one way in the numerator and another way in the denominator

What are qualitative descriptions?

refers to the identity or form of a substance present

What are quantitative measurements?

Experiments that determine the amount of a substance present

What are exact numbers?

Defined values or counting

Examples of exact numbers

Defined values: 1kg = 1000g OR 1 dozen = 12 objects

Counting: 28 students in a class

What are inexaxt numbers?

Any method other than counting

Examples of inexact numbers

Length, mass, volume, time, and speed

What is a significant figure?

the meaningful digits in a reported number

Rules of significant figures

1. any nonzero digit is significant

2. zeros between nonzero digits are significant

3. zeros to the left of first nonzero digit are not significant

4. zeros to the right of the last nonzero digit are significant IF a decimal is present

5. zeros to the right of the last nonzero digit that do NOT contain a decimal are ambigous