Chemistry Exam

Biochemistry → Chemistry of living things

Organic chemistry → Study of carbon-containing compounds

Atom → Smallest unit of matter that keeps chemical identity

Compound → Two or more chemically bonded atoms

Mass → Amount of matter

Matter → Anything with mass and volume

Physical change → Changes form, not identity

Chemical change → Forms a new substance

Noble gases → Unreactive elements (Group 18)

Mixture → Substances physically combined

Heterogeneous mixture → Uneven composition (granite)

Group → Vertical column on periodic table

Period → Horizontal row on periodic table

Nonmetals → Brittle, poor conductors

Metalloids → Semiconductors

Mendeleev → Arranged elements by atomic mass

Moseley → Arranged elements by atomic number

Lanthanides → Atomic numbers 58–71

Actinides → Atomic numbers 90–103

Halogens → Group 17, very reactive

Valence electrons → Electrons in outer energy level

Ionization energy → Energy needed to remove an electron

Atomic radius → Half the distance between bonded nuclei

Electronegativity → Ability to attract electrons

Cation → Positive ion

Anion → Negative ion

Covalent bond → Electrons shared

Ionic bond → Electron transfer

Metallic bond → Positive ions + mobile electrons

Polar molecule → Uneven charge distribution

Photon → Quantum of light energy

Aufbau principle → Lowest energy orbitals fill first

Hund’s rule → One electron per orbital before pairing

Pauli exclusion principle → No two electrons identical

Ground state → Lowest energy state

Excited state → Higher energy state