Chemistry Basics: Terminology and Measurement Review

Vocabulary flashcards covering core chemistry terms and related measurement concepts from the notes.

Chemistry

The science dealing with the identification of substances of matter, their properties, interactions, and changes that form new substances.

Matter

Anything that occupies space and has mass.

Substance

Matter with a definite composition and distinct properties.

Element

A substance that cannot be chemically broken down into simpler substances; defined by a unique number of protons.

Compound

A substance made of two or more elements chemically combined in fixed proportions.

Mixture

A combination of two or more substances that can be separated by physical means.

Homogeneous mixture

A mixture with uniform composition throughout.

Heterogeneous mixture

A mixture whose composition is not uniform throughout.

Atom

The basic unit of a chemical element; the smallest unit that retains the element’s identity.

Molecule

Two or more atoms bonded together in a specific geometrical arrangement.

Bond

Forces that hold atoms together in a substance.

Physical change

A change in which the substance’s form or appearance changes but its composition remains the same.

Chemical change

A transformation that changes the substance’s composition.

Solid

State of matter with fixed shape and volume; particles are tightly packed.

Liquid

State of matter with definite volume but takes the shape of its container; particles are less tightly packed than a solid.

Gas

State of matter with no fixed shape or volume; particles are far apart and highly compressible.

Mass

A measure of the amount of matter in an object, typically in grams.

Volume

The amount of space an object occupies; common units include mL and L.

Density

Mass per unit volume; d = mass/volume.

Temperature

A measure of the average kinetic energy of particles; scales include Celsius, Kelvin, and Fahrenheit.

Qualitative vs Quantitative

Qualitative: observations without numbers; Quantitative: measurements with numbers.

Exact numbers

Numbers defined by counting or preset definitions with no uncertainty (e.g., 1000 mg = 1 g).

Measured numbers

Numbers obtained from instruments with some uncertainty.

Precision

Closeness of a set of measurements to each other.

Accuracy

Closeness of a measurement to the true value.

Standard deviation

A statistic that measures the spread of a set of data (a measure of precision).

Percent error

A measure of accuracy comparing experimental value to true value expressed as a percentage.

Significant figures

Digits that carry the precision of a measurement, including the uncertain last digit.

Scientific notation

A compact form to express numbers as a value between 1 and 10 multiplied by a power of 10.

Metric prefixes

Prefixes indicating powers of ten (e.g., kilo- 10^3, milli- 10^-3, micro- 10^-6).

SI units

International System of Units: meter (length), gram (mass), liter (volume), second (time), kelvin (temperature), etc.

Mole

The amount of substance containing 6.022×10^23 entities (Avogadro’s number).

Molar mass

Mass of one mole of a substance, in g/mol; numerically equal to the formula weight in amu.

Formula weight

Sum of the atomic masses in a formula unit (in amu).

Avogadro’s number

6.022×10^23 entities per mole.

Isotope

Atoms of the same element with different numbers of neutrons, hence different mass numbers.

Ion

An atom or molecule with a net electric charge due to loss or gain of electrons.

Cation

A positively charged ion.

Anion

A negatively charged ion.

Atomic number (Z)

The number of protons in the nucleus of an atom.

Mass number (A)

The total number of protons and neutrons in the nucleus.

Periodic table

An arrangement of elements in rows (periods) and columns (groups) by properties.

Metals vs Nonmetals

Metals: good conductors, shiny, malleable; Nonmetals: poor conductors, varied states; electrons transfer in ionic bonds.

Ionic bond

Bond formed by transfer of electrons resulting in charged ions attracted to each other.

Covalent bond

Bond formed by sharing electrons between atoms.

Polyatomic ion

A charged species composed of two or more atoms.

Hydrate

An ionic compound with a specific number of water molecules attached.

Acid (Arrhenius)

A substance that increases H+ in aqueous solution (contains H+ and a nonmetal or polyatomic anion).

Base (Arrhenius)

A substance that increases OH- in aqueous solution or accepts H+.

Empirical formula

The simplest whole-number ratio of atoms in a compound.

Molecular formula

The actual number of each type of atom in a molecule; may be a multiple of the empirical formula.

Percent composition

The mass percentage of each element in a compound.

Stoichiometry (molar ratios)

The calculation of reactants and products in chemical reactions using balanced equations and mole ratios.

Chemistry

The science dealing with the identification of substances of matter, their properties, interactions, and changes that form new substances.

Matter

Anything that occupies space and has mass.

Substance

Matter with a definite composition and distinct properties.

Element

A substance that cannot be chemically broken down into simpler substances; defined by a unique number of protons.

Compound

A substance made of two or more elements chemically combined in fixed proportions.

Mixture

A combination of two or more substances that can be separated by physical means.

Homogeneous mixture

A mixture with uniform composition throughout.

Heterogeneous mixture

A mixture whose composition is not uniform throughout.

Atom

The basic unit of a chemical element; the smallest unit that retains the element’s identity.

Molecule

Two or more atoms bonded together in a specific geometrical arrangement.

Bond

Forces that hold atoms together in a substance.

Physical change

A change in which the substance’s form or appearance changes but its composition remains the same.

Chemical change

A transformation that changes the substance’s composition.

Solid

State of matter with fixed shape and volume; particles are tightly packed.

Liquid

State of matter with definite volume but takes the shape of its container; particles are less tightly packed than a solid.

Gas

State of matter with no fixed shape or volume; particles are far apart and highly compressible.

Mass

A measure of the amount of matter in an object, typically in grams.

Volume

The amount of space an object occupies; common units include mL and L.

Density

Mass per unit volume; d = \frac{\text{mass}}{\text{volume}}.

Temperature

A measure of the average kinetic energy of particles; scales include Celsius, Kelvin, and Fahrenheit.

Qualitative vs Quantitative

Qualitative: observations without numbers; Quantitative: measurements with numbers.

Exact numbers

Numbers defined by counting or preset definitions with no uncertainty (e.g., 1000 mg = 1 g).

Measured numbers

Numbers obtained from instruments with some uncertainty.

Precision

Closeness of a set of measurements to each other.

Accuracy

Closeness of a measurement to the true value.

Standard deviation

A statistic that measures the spread of a set of data (a measure of precision).

Percent error

A measure of accuracy comparing experimental value to true value expressed as a percentage.

Significant figures

Digits that carry the precision of a measurement, including the uncertain last digit.

Scientific notation

A compact form to express numbers as a value between 1 and 10 multiplied by a power of 10.

Metric prefixes

Prefixes indicating powers of ten (e.g., kilo- 10^3, milli- 10^{-3}, micro- 10^{-6}).

SI units

International System of Units: meter (length), gram (mass), liter (volume), second (time), kelvin (temperature), etc.

Mole

The amount of substance containing 6.022 \times 10^{23} entities (Avogadro’s number).

Molar mass

Mass of one mole of a substance, in g/mol; numerically equal to the formula weight in amu.

Formula weight

Sum of the atomic masses in a formula unit (in amu).

Avogadro’s number

6.022 \times 10^{23} entities per mole.

Isotope

Atoms of the same element with different numbers of neutrons, hence different mass numbers.

Ion

An atom or molecule with a net electric charge due to loss or gain of electrons.

Cation

A positively charged ion.

Anion

A negatively charged ion.

Atomic number (Z)

The number of protons in the nucleus of an atom.

Mass number (A)

The total number of protons and neutrons in the nucleus.

Periodic table

An arrangement of elements in rows (periods) and columns (groups) by properties.

Metals vs Nonmetals

Metals: good conductors, shiny, malleable; Nonmetals: poor conductors, varied states; electrons transfer in ionic bonds.

Ionic bond

Bond formed by transfer of electrons resulting in charged ions attracted to each other.

Covalent bond

Bond formed by sharing electrons between atoms.

Polyatomic ion

A charged species composed of two or more atoms.