Facts

Observations we make about the world around us

Hypothesis

-a proposed explanation for a phenomenon made as a starting point for further investigation -must be testable, not something we prove

Theory

-a well-substantiated explanation acquired through the scientific method and repeatedly tested and observed through observation and experimentation

Law

-a statement based on repeated experimental observation that describes some phenomenon of nature -not disputable

Chemistry

the study of matter and how it and energy changes

Organic chemistry

the study of hydrocarbons

Inorganic chemistry

the study of everything that is not a hydrocarbon

Physical chemistry

the study of macro-components

Analytical chemistry

the study of micro-components

Biochemistry

the study of life chemistry

Theoretical chemistry

the study of mathematical chemistry

Matter

anything that has mass and takes up space

Pure substance

-uniform by looks and definite chemical composition -created or separated by chemical change -100% one substance (ex. H2O)

Mixture

-two or more substances physically combined or separated -no set ratio of parts

Element

-the simplest form of matter that can't be broken down -one type of atom -metals, nonmetals, or metalloids -diatomic molecule elements (ex. H2, N2)

Compound

-a uniform substance formed when two or more elements combine/bond chemically (ex. CO2)

Homogenous mixture

-looks the same throughout -solutions -miscible (dissolved) -ex. flat soda, water

Heterogeneous mixture

-not uniformly mixed (you can see different parts) -suspension -immiscible (not dissolved) -if you need to shake or stir, it is hetero -ex. noodle soup, paint

How to identify atoms and elements

chemical symbols

How to express a compound

chemical formulas

Gases/Vapors

-no definite shape -no definite volume -particles spread out -fastest particle motion (flow) -most kinetic energy

Liquids

-no definite shape (takes shape of the container) -definite volume -disorderly arrangement of particles (still closer together) -particles flow

Solids

-definite shape -definite volume -orderly arrangement of particles -particles vibrate in place

Physical property

-property of matter observed or measured without changing the composition of the substance -ex. solubility, density, color, mass

What are the 2 types of physical properties?

extensive and intensive

Extensive properties

-dependent on the amount of matter -the only examples are mass, volume, length -by changing the amount, mass, volume, or length would change

Intensive properties

-independent to the amount of matter -ex. density, melting, boiling points -it does not matter how much of a substance we have

If you are lost on a test, and need to guess intensive or extensive, always guess...

intensive!!!

Chemical property

-property that describes how matter reacts to form new substances -flammability -corrosive

Flammability

substance reacting to fire

Corrosive

metals reacting with acid/water

Physical changes

-a change that alters a substance without changing its composition -all phase changes (IMF change) -mixture separation

What type of change is solid going to liquid and liquid going to gas?

physical change

What is the process called when a solid turns to a liquid?

melting

What is the process called when a liquid turns into a gas?

evaporation/boiling

What is the process called when a gas turns into a liquid?

condensation

What is the process called when a liquid turns into a solid?

freezing

When going from a solid to a gas the heat is...

-increasing (adding heat) -endothermic

When going from a gas to a solid the heat is...

-decreasing (removing heat) -exothermic

Exothermic

attraction

Endothermic

breaks attraction

What is the process called when a solid turns into a gas?

sublimation

What is the process called when a gas turns into a solid?

deposition

Chemical change

-any change when one or more substances are converted into new substances -chemical reactions

What are the 4 signs of chemical change (reaction)?

1. formation of gas 2. precipitate 3. evolution of heat or light 4. color change

Is a solid, liquid, or gas a precipitate?

solid

Chemical equation

-a description of a chemical reaction -ex. 2C + 2O2 = 2C2

Law of Conservation of Mass states that...

-matter cannot be created or destroyed -matter changes state (solid, liquid, gas) or particles are rearranged -mass before = mass after