Chemistry Test #1 Key Terms

Composition

how something is put together / arranged

Allotrope

a different form of the same element

Precision

being exact and accurate

Neutralization

acid + base = salt + H2O

Filtration

a way to separate a solid from a liquid

Ductility

the ability to be stretched into a wire

Compound

a substance composed of two or more different elements bonded together in fixed (definite) ratios. Can be decomposed into the elements that compose them (homogeneous and heterogeneous mixtures). They have a unique set of properties that are different from the elements that compose them.

Equation

a way to show a chemical reaction using chemical formulas

Evaporation

when a liquid changes into a gas because of added energy

Chemical property

descriptions of chemical reactivity. New substance(s) is/are formed during a chemical reaction. When you see the word react or reaction it is a chemical property.

Nuclear change

a change of one atom into another = transmutation. Elemental symbols change from reactants into products with no conservation of mass

Mixture

a combination of two or more substances that in the same space don't react / bond to form a new substance. Ex. salt water, wedding rings, chocolate chip cookies. Mixtures can be heterogeneous or homogeneous. A mixture can be separated by physical means (using different physical properties)

Diatomic

groups of 2 atom molecules

Percentage error

how far a measured value is from the actual value shown as a percentage

Molecule

the smallest particle of a sample that retains the properties of that sample.

Decomposition

all compounds can be decomposed

Malleability

this is when you hit metals with a hammer and they flatten out

Conductivity

the ability of a material to let heat / electricity pass through it

Homogeneous

also called solutions, they have a uniform consistency throughout the sample. Ex. dissolved oxygen, sugar water, and air, alloys, tinctures

Solubility

how well a substance dissolves in another substance

Significant figure

All the certain and estimated digits in a measurement. If there is a decimal point → “Start left, count right” If there is no decimal point → “Start right, count left”. When using multiplication or division, the final answer should be rounded to the least number of significant figures of anything that was divided or multiplied.

Chemical change

New substances are formed, the chemical formulas of reactants and products change and the law of conservation of mass is followed. Chemical changes tend to produce color changes, gases, and energy changes.

Element

a substance composed of one type of atom that can not be broken down by chemical means. The smallest unit can be one, two, or even more atoms. Some elements have more than one form that differ in their crystal structure and properties.

S,l,g and aq

s = solid, l = liquid, g = gas, aq= aqueous which means dissolved in water.

Corrosion

“rust” when a material slowly breaks down because of a chemical reaction

Monatomic

1 atom

Accuracy

how close a measurement is to the correct value

Transmutation

when one element changes into a different element

Precision

how close repeated measurements are to one another

Filtrate

the liquid that passes through a filter

Chromatography

a method used to separate different parts of a mixture. Ex. used in bio for plants

Formula

a way to show what a substance is made of using chemical symbols

Distillation

a method used to separate substances by heating and cooling them

Physical property

can be observed without changing the composition of the sample. Ex. color, smell, boiling point, melting point

Physical change

change in appearance. Same substances before and after the change, the law of conservation of mass holds true. It will have the same chemical formula on both sides of the equation.

Heterogeneous

have a non-uniform consistency throughout the sample. Ex. oil and water, sand and water. *You see layers / see different particles

Substance

includes elements and compounds which are homogeneous.

HOFBrINCl

stands for hydrogen, oxygen, fluorine, bromine, iodine, nitrogen, and chlorine which are all diatomic elements.