General Chemistry: Atoms, Periodic Table, and Measurement

Vocabulary practice flashcards covering fundamental chemistry concepts, atomic structure, the periodic table, stoichiometry basics, measurements, states of matter, and chemical vs physical changes.

Chemistry

The study of matter and the changes that matter undergoes.

Matter

Anything that has mass and occupies space.

Atom

The smallest quantity of matter that still retains the properties of matter.

Electron

A negatively charged subatomic particle found outside the nucleus of an atom, with a charge of $1-$ and a mass of approximately $0.00055\,\text{amu}$.

Proton

A positively charged subatomic particle found in the nucleus, with a charge of $1+$ and a mass of approximately $1.007\,\text{amu}$.

Neutron

A subatomic particle found in the nucleus with no charge ($0$) and a mass of approximately $1.008\,\text{amu}$.

Nucleus

The small, extremely dense center of an atom that contains protons and neutrons and accounts for almost all of the atom's mass.

Isotopes

Atoms with the same number of protons but different numbers of neutrons, exhibiting almost identical chemical properties.

Period

A horizontal row of elements on the periodic table.

Group

A vertical column of elements on the periodic table that contain elements with similar chemical properties.

Alkali Metals

The Group 1A elements on the periodic table, consisting of Li, Na, K, Rb, Cs, and Fr.

Alkaline Earth Metals

The Group 2A elements on the periodic table, consisting of Be, Mg, Ca, Sr, Ba, and Ra.

Chalcogens

The Group 6A elements on the periodic table, consisting of O, S, Se, Te, and Po.

Halogens

The Group 7A elements on the periodic table, consisting of F, Cl, Br, I, and At.

Noble Gases

The Group 8A elements on the periodic table, consisting of He, Ne, Ar, Kr, Xe, and Rn.

Metal

An element characterized by shiny luster, high thermal and electrical conductivity, malleability, ductility, and existing as a solid at room temperature (except mercury).

Nonmetal

An element that lacks metallic properties, is typically a poor conductor of heat and electricity, and can exist as a solid, liquid, or gas at room temperature.

Metalloid

An element that exhibits properties intermediate between metals and nonmetals, several of which function as electrical semiconductors.

Mole

The amount of a substance that contains as many elementary entities as there are atoms in exactly $12\,\text{g}$ of carbon-12.

Avogadro's Number

The experimentally determined number of elementary entities in one mole of a substance, equal to $6.022 \times 10^{23}$ (or $6.02 \times 10^{23}$).

Molar Mass

The mass in grams of one mole of a substance, serving as the conversion factor between mass in grams and amount in moles.

Molecule

Two or more atoms joined and acting as a unit.

Compound

Two or more different atoms joined and acting as a unit.

Chemical Reaction

A process in which one substance changes into another by reorganizing the way the atoms are attached to each other.

Theory

A set of tested hypotheses that gives an overall explanation of some natural phenomenon.

Scientific Law

A theory that has been tested and found to be true over a long period of time (usually 20+ years) with no counterexamples.

Measurement

A quantitative observation consisting of two parts: a number and a scale (unit).

Accuracy

The degree of agreement of a particular value with the true value.

Precision

The degree of agreement among several measurements of the same quantity.

Leading Zeros

Zeros that precede all non-zero digits, which never count as significant figures.

Captive Zeros

Zeros positioned between non-zero digits, which always count as significant figures.

Trailing Zeros

Zeros at the right end of a number, which count as significant figures only if the number contains a decimal point.

Exact Numbers

Numbers derived from counting or defined conversion factors that possess an infinite number of significant figures.

Solid State

A state of matter that is rigid, having a fixed volume and a fixed shape.

Liquid State

A state of matter that has a definite volume but no specific shape, assuming the shape of its container.

Gas State

A state of matter that has no fixed volume or shape, taking on both the shape and volume of its container.

Homogeneous Mixture

A mixture having visibly indistinguishable parts, also referred to as a solution.

Heterogeneous Mixture

A mixture having visibly distinguishable parts.

Physical Change

A change in the form of a substance that does not alter its chemical composition.

Chemical Change

A process in which a given substance becomes a new substance or substances with different properties and composition.

Density

The ratio of a substance's mass to its volume, given by $\frac{\text{Mass}}{\text{Volume}}$ .

Mass Number

The total number of protons and neutrons in an atomic nucleus, represented by the letter $A$ in atomic notation.

Atomic Number

The total number of protons in the nucleus of an atom, represented by the letter $Z$ in atomic notation.