Chemistry Final

• 1. Making observations
• 2. Testing hypotheses
• 3. Developing theories

a well-tested explanation for a broad set of observations

a repeatable procedure that is used to test a hypothesis

a proposed explanation for an observation

information obtained through the senses; observation in science often involve a measurment

A concise statement that summarizes the results of many observations and experiments

To draw a conclusion based on what one already knows

• Solid
• Liquid
• Gas

• Form of matter that has a definite shape and volume.
• Particles are packed tightly together, orderly arrangement.

• Form of matter that has an indefinite shape, flows, yet has a fixed volume.
• Particles are free to flow.

• Form of matter that takes both the shape and volume of the container.
• Particles move fast and are much farther apart.

• Chemical: change that produces matter with a different composition than the original matter
• Physical: change during which some properties change but the composition stays the same

Compounds can be broken down into simpler substances by chemical means, but elements cannot.

a substance that contains two or more elements chemically combined

the simplest form of matter that has a unique set of properties; can't be broken down into simpler substances by chemical means

the ability of a substance to undergo a specific chemical change

a quality or condition of a substance that can be observed or measured without changing the composition

a one or two letter representation of an element

mixture that is not uniform in composition; components aren't evenly distributed throughout the mixture

mixture that is uniform in composition; evenly distributed and not easily distinguished

matter that has a uniform and definite composition

a homogeneous mixture; consists of solutes dissolved in a solvent

dissolved particles in a solution

dissolving medium in a solution

mass can be neither created nor destroyed

the zero point on the Kelvin temperature scale; -273.15 degrees C

a quantity used by general agreement of the scientific community

the closeness of a measurement to the true value of what is being measured

describes the closeness of a set of measurements taken under the same condition

• ratio of the mass of an object to its volume
• D=m/v

a quantitative value measured during an experiment

all the digits that can be known precisely in a measurement, plus a last estimated digit

Percent Error= error/accepted value  x 100%

• centimeter (cm)
• meter (m)
• kilometer (km)

• liter (L)
• milliliter (mL)
• cubic centimeter (cm3)
• microliter

• kilogram (kg)
• gram (g)
• milligram (mg)
• microgram

• Kelvin scale
• Celsius scale
• K=C+273
• C=K-273

used to describe what the object is like; cannot be definitively measured

something that can be counted or measured

any atom or group of atoms with a negative charge

any atom or group of atoms with a positive charge

• a compound composed of two elements
• examples: NaCl and Al₂O₃ 

a compound composed of positive and negative ions

a compound composed of molecules

the lowest whole-number ration of ions in an ionic compound

a neutral group of atoms joined together by covalent bonds

An atom or group of atoms that has a positive or negative charge

a single atom with a positive or negative charge resulting from the loss or gain of one or more valence electrons

a tightly bound group of atoms that behaves as a unit and has a positive or negative charge

a compound containing three different elements

a chemical equation that doesn't indicate the relative amounts of reactants and products

a chemical equation in which mass is conserved; each side of the equation has the same number of atoms of each element

• substance that increases the rate of reaction
• not used up in the reaction

a small whole number that appears in front of a formula in a balanced equation

a chemical change in which two or more substances react to form a single new substance

a chemical change in which an element or a compound reacts with oxygen; often produces energy in the form of light and heat

a chemical change in which a single compound is broken down into two or more simpler products

a chemical change in which one element replaces a second element in a compound

a chemical change that involves an exchange of positive ions between two compounds

an equation for a reaction in solution showing only those particles that are directly involved in the chemical change

an ion that isn't directly involved in a chemical reaction

number that is written below the element that lets you know how many molecules of that element are present

the amount of a substance that contains 6.02 x 10²³ representative particles of the substance

6.02 X 10²³

mass of a mole of any substance

the percent by mass of each element in a compound

a formula with the lowest whole-number ratio of elements in a compound

a chemical formula of a molecular compound that shows the kinds and numbers of atoms present in a molecule of a compound

the conditions under which the volume of a gas is usually measured