Chemistry I PLTL Notes: Atoms, Periodic Table, and Compounds (Vocabulary)

A set of vocabulary-style flashcards covering metals vs. nonmetals, atomic structure, isotopes, periodic table terminology, ionic/molecular compounds, formulas, and basic reaction concepts.

Metals

Elements that are good conductors of heat and electricity; generally donate electrons in reactions.

Nonmetals

Elements that are poor conductors of heat and electricity; tend to gain electrons in reactions.

Metalloids

Elements with intermediate properties between metals and nonmetals.

Periodic table

A tabular arrangement of elements organized by increasing atomic number, showing groups and periods.

Group (in the periodic table)

A column of elements; elements in the same group have similar chemical properties.

Period (in the periodic table)

A row of elements; represents the energy level structure of atoms.

Atoms

The basic units of matter composed of protons, neutrons, and electrons.

Proton

Positively charged subatomic particle in the nucleus.

Neutron

Electrically neutral subatomic particle in the nucleus.

Electron

Negatively charged subatomic particle orbiting the nucleus.

Atomic number

Number of protons in an atom; equals the number of electrons in a neutral atom.

Mass number

Sum of protons and neutrons in the nucleus.

Atomic mass

Weighted average mass of an element’s atoms, measured in atomic mass units (amu).

Atomic mass unit (amu)

Unit used to express atomic and molecular weights.

Isotopes

Atoms of the same element with different mass numbers due to differing neutron counts.

Uranium-235 and Uranium-238

Isotopes of uranium with the same atomic number but different mass numbers.

Ion

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

Cation

A positively charged ion formed when an atom loses electrons.

Anion

A negatively charged ion formed when an atom gains electrons.

Ionic compound

Compound composed of cations and anions held together by electrostatic forces.

FeSO4

Iron(II) sulfate; an ionic compound containing Fe2+ and sulfate ions.

Fe2(SO4)3

Iron(III) sulfate; an ionic compound containing Fe3+ and sulfate ions.

Molecular (covalent) compound

Compound formed when nonmetals share electrons.

Empirical formula

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

Molecular formula

The actual number of atoms of each element in a molecule.

Empirical vs molecular formula

Empirical shows the simplest ratio; molecular shows the exact number of atoms in a molecule.

Balancing chemical equations

Process of adjusting coefficients so the number of each type of atom is the same on both sides.

Coefficient

The number in front of a formula in a chemical equation that balances the equation.

Percent by mass

The mass percentage of each element in a compound.

Sodium bicarbonate

NaHCO3; common compound known as baking soda.

Sodium hydroxide and hydrochloric acid reaction

NaOH + HCl → NaCl + H2O; an example of a neutralization reaction.

Ba(OH)2 + 2HCl reaction

Barium hydroxide reacts with hydrochloric acid to form BaCl2 and H2O.

Zinc and silver chloride reaction

Zn + 2 AgCl → ZnCl2 + 2 Ag; displacement reaction.

Noble gases

Group 8A elements; highly unreactive due to full valence electron shells.

Halogens

Group 7A elements; highly reactive nonmetals.

Alkaline earth metals

Group 2A metals; reactive metals with two valence electrons.