Matter
Anything that has mass and occupies space; all matter is composed of atoms
Atom
Smallest unit of a chemical element; physical and chemical properties of atoms (how they interact with other atoms) depends on the number of particles the atom contains
Proton
Subatomic particle, positive electrical charge, located in the atom’s nucleus
Neutron
Subatomic particle, no charge, located in the atom’s nucleus
Electron
Subatomic particle, negative electrical charge, located in orbits around the atoms nucleus; the farther an electron is from the nucleus - the more energy the electrons has
Valence shell
An atom’s outer most energy shell (a fixed distance from the nucleus )
Valence electrons are involved in
Chemical reactivity
Element
A substance that cannot be converted into simpler substances by ordinary chemicals
Compound
A substance made up of atoms of more that one element
Molecule
A chemical substance made up of two or more atoms joined by covalent or ionic bonds
Chemical bond
An attractive force that links two atoms together In molecule
Electron negativity
The attraction of a given atom for the electrons of a covalent bond, the more electronegative an atom is, the more strongly is pulls shared towards electrons itself; this can cause an unequal sharing of electrons
Covalent bonds
Formed when two atoms attain stable electron numbers in their valence shell by sharing (equal or unequal) a pair of electrons
Polar covalent bonds
Unequal sharing electrons
Non polar covalent bonds
Equal sharing of electrons
Ion
An electrically charged particle that forms when atom gains or loses one or more electron
Cation
Positively charged ion
Anion
Negatively charged ion
Ionic bond
A chemical bond resulting from the electrical attraction between oppositely charged ions, ions can form ionic bonds that result in stable solid compounds called cats
Hydrogen bond
A weak chemical bond that is formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond din another molecule or in another region of the same molecule; form between water molecules; DNA and proteins
Polar molecules that form hydrogen bonds are considered
Hydrophilic “water loving”
No polar molecules such as hydrocarbons are
Hydrophobic “water fearing”
Van der waals forces
Weak attractions between molecules or parts of molecule that result from transient local partial charges, one-fourth of the strength of a hydrogen bonds
Chemical reactions
Occur when atoms collide with enough energy to combine or change their bonding partners; the making and breaking of chemical bonds lead to changed in the composition of matter
