Basic Chemistry

Matter

anything that has mass and takes up space

Elements

purest form of matter

Atoms

smallest unit of matter that maintains unique properties

Nucleus

central part of atom that has mass, but negligible volume. Protons and neutrons

Protons

have a mass of 1 AMU; +1 charge

Neutrons

1 AMU; no charge

Atomic Mass

protons + neutrons

Identity of atom

Determined by atomic number

Atomic number

number of protons

Isotope

atoms of the same element with different numbers of neutrons

Mass

average mass of all isotopes

Electron cloud

mostly empty space that gives atom volume with negligible mass

Electrons (e-)

0 AMU, -1 charge; determine chemical behavior

Neutral atoms

electrons = protons (e- = H+)

Ion

atoms with unequal electrons to protons

Atom gains electron

Holds negative charge

Atom loses electron

Holds positive charge

1st Electron Shell

Closest to nucleus; 2 e- max

2nd/3rd Electron Shell

4 orbitals holds 2e- each, equaling 8e-

Bohr Model

depicts total e- arrangement

Lewis Dot Structure

indicates valance electrons only (outermost shell)

Covalent Bond

• sharing electrons between 2 atoms to complete e- pair

• indicated by stick between atom

Non-polar covalent bonds

• e- shared equally between atoms

• hydrophobic

Polar covalent bonds

• one atom “hogs” the electrons

• occurs when one atom is more electronegative (e- affinity)

• creates partial charges: more negative around more electronegative and vice versa

Ionic Bond

atoms held together by opposite charges

Ion

charged atom (losing or gaining electrons)

Hydrogen Bond

work due to partial charge interaction (found in molecules w/ polar covalent bonds; represented by dashed line) (weak interaction)

Van der Waal Interaction

weak interaction due to distance between molecules

Hydrophobic Interactions

Non-polar molecules aggregate in polar solvent

Chemical Reactions

making or breaking of chemical bonds, creates new forms of matter