Chem exam 1 review

Matter

anything that occupies space and has mass

Mass

fundamental property indicating amount of matter

Weight

force that gravity exerts on an object

Law of Conservation of Matter

when matter converts from one type to another or changes form, there is no detectable change in the total amount of matter present

Matter can be classified into what two categories

mixtures and pure substances

Pure Substances

homogeneous substance that has a constant composition

Mixtures

matter that can be separated into its components by physical means

ex/ evaporation

What are the 2 classes that pure substances can be divided into

elements and compounds

Elements

substance that is composed of a single type of atom; a substance that cannot be decomposed by a chemical change

compound

pure substance that can be decomposed into two or more elements

heterogeneous mixture

combination of substances with a composition that varies from point to point

homogeneous mixture

(also, solution) combination of substances with a composition that is uniform throughout

Measurement

values: accuracy, precision, certainty

unit

standard of comparison for measurements

accuracy

how closely a measurement aligns with a correct value

(aka “the real value”)

precision

how closely a measurement matches the same measurement when repeated

how consistent and detailed your measurements are

(i.e., how close they are to each other)

consistent

Certainty

how confident we can be in the specificity of the measurement

(i.e., how much do we really know about the measurement?)

The number in the measurement can be represented in different ways, including ____ and _____.

Decimal Form; Scientific Notation

significant figures

(also, significant digits) all of the measured digits in a determination, including the uncertain last digit

digits that are meaningful in a measurement

The Uncertain Digit

One more than our measurement tool can tell us for sure

SI units (International System of Units)

standards fixed by international agreement in the International System of Units (Le Système International d’Unités)

meter (m)

standard metric and SI unit of length; 1 m = approximately 1.094 yards

kilogram (kg)

standard SI unit of mass

second (s)

SI unit of time

kelvin (K)

SI unit of temperature; 273.15 K = 0 ºC

volume

amount of space occupied by an object

density

ratio of mass to volume for a substance or object

cubic meter (m³)

SI unit of volume

cubic centimeter (cm³ or cc)

volume of a cube with an edge length of exactly 1 cm

atom

molecule

bonded collection of two or more atoms of the same or different elements

milliliter (mL)

1/1,000 of a liter; equal to 1 cm³

liter (L)

(also, cubic decimeter) unit of volume; 1 L = 1,000 cm³

atomic mass

average mass of atoms of an element, expressed in amu

total # of protons and neutrons

Dalton’s atomic theory

set of postulates that established the fundamental properties of atoms

electron

negatively charged, subatomic particle of relatively low mass located outside the nucleus

proton

positively charged, subatomic particle located in the nucleus

neutron

uncharged, subatomic particle located in the nucleus

atomic mass unit (amu)

(also, unified atomic mass unit, u, or Dalton, Da) unit of mass equal to 112 of the mass of a ¹²C atom

ion

electrically charged atom or molecule (contains unequal numbers of protons and electrons)