Life and Chemistry: Small Molecules

The number of protons in an atom's nucleus, unique to each element.

Atoms of the same element with different numbers of neutrons.

Unstable atomic nuclei that decay, releasing energy and particles.

The region around the nucleus where an electron is likely to be found.

Ordered areas around the nucleus, where electrons orbit.

The first orbital in an electron shell, filling first.

Orbital in electron shells beyond the first.

The central core of an atom containing protons and neutrons.

The outermost electron shell of an atom, determining how it reacts with other atoms.

Electrons in the valence shell, influencing an atom's reactivity.

The tendency of atoms to have eight electrons in their outermost shell to become stable.

An attraction force linking two or more atoms together.

A chemical bond formed by sharing electron pairs between atoms.

Two or more atoms bonded together.

An energy level around the nucleus where electrons are found.

The number of unpaired valence electrons in an atom.

Covalent bonds are very strong chemical bonds that hold atoms together by sharing electrons.

A covalent bond where electrons are unequally shared, creating partial positive and partial negative charges on atoms.

An atom's ability to attract electrons in a chemical bond.

The sum of the masses of all atoms in a molecule.

A unit of measurement representing 6.022 x 10^23 molecules or entities.

Concentration of a substance in a solution, measured as moles per liter.

Atoms sharing two pairs of electrons.

Molecules with polar covalent bonds; possessing unevenly distributed charges.

Weak attractions between molecules with polar covalent bonds. The positive part of one molecule is attracted to the negative part of another.

Bonds formed by the transfer of electrons, creating charged ions (cations and anions) that attract each other.

Molecules with uneven distribution of charges, creating slightly positive and negative poles.

Molecules with an even distribution of charge, no separation of poles; don't dissolve well in water.

Molecules attracted to water; polar molecules typically.

Molecules repelled by water; nonpolar molecules typically.

Process where atoms rearrange, forming new bonds and breaking old ones.

Reactants are substances initially present and changed into products, substances created during a reaction.

Chemical equations must balance because matter is neither created nor destroyed in a chemical reaction.

Chemical reactions often involve changes in energy, usually related to potential energy stored in chemical bonds.

Stored energy, like that in chemical bonds, is called potential energy and can be measured using units of heat.

A calorie is the amount of heat energy to raise one gram of pure water by 1°C.

Water is the solvent in living organisms where many reactions take place.

A mole is a quantity of a substance equal to its molecular weight in grams and contains approximately 6.022 x 10^23 molecules.

A 1 molar solution contains one mole of a compound dissolved in one liter of water.

Water's bent shape, polarity, and ability to bond unusually affect its properties, like ice being less dense than liquid water.

Ice is less dense than liquid water, causing it to float on top.

A large amount of heat is needed to change water's temperature.

Hydrogen bonds between water molecules influence its properties.

Water molecules stick together due to hydrogen bonds.

Water molecules stick to other substances.

The surface of water is resistant to external forces due to water's cohesion.

Substances that release Hydrogen ions (H+) when dissolved in water.

Substances that release hydroxide ions (OH-) when dissolved in water.