Unit 5 Flashcards
a mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together.
Chemical Bond
forms from the transfer of valence electrons. This forms between cations and anions (metals and nonmetals). Compounds with this type of bond have high melting points and are hard and brittle.
Ionic Bond
forms when valence electrons are shared between two or more nonmetals (usually nonmetals or metalloids).
Covalent (molecular) Bond
bonds in which there is an uneven distribution of electrical charge. These compounds are soluble in water. (ex. H2O and NH3) They are not symmetrical.
Polar Covalent Bonds
bonds in which there is an even distribution of charge. (ex. carbon tetrachloride, CCl4) They are not soluble in water.
Nonpolar Covalent Bonds
charged particles. These are atoms that have either lost or gained valence electrons. They participate in the bonding of metals and nonmetals.
Ions
positive ions (mostly metals). These form when an atom loses its valence electrons.
Cations
negative ions (mostly nonmetals). These form when an atom gains valence electrons.
Anions
a neutral group of atoms, nonmetals, held together by covalent bonds.
Molecule
a chemical compound whose simplest units are molecules (ex. NH3)
Molecular Compound
indicates the relative number of each atom in a compound using the element symbols and numerical subscripts (ex. sodium sulfate = Na2SO4)
Chemical Formula
same as a chemical formula, but contains nonmetals only.
Molecular Formula
Start with “hydro-“ and end with “-ic” and acids, when naming.
Binary Acids
When naming:
If the anion ends in “-ite” and the acid ends in “-ous” and then add the word acid.
If the anion ends in “-ate” and the acid ends in “-ic” and then add the word acid.
Ternary Acids
determining the percentage of each element found in a compound
Percent Composition
compounds, usually salts, that have water physically attached to them. When these compounds are heated, the water evaporates leaving behind the anhydrous salt.
Hydrates
without water
Anhydrous
a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample you have. Sodium chloride, for example, is always NaCl, not NaCl2 or some other combination
Law of Definite Proportions
If two or more compounds are composed of the same elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers.
Law of Multiple Proportions
the simplest whole-number ratio of a compound
Empirical Formula
the actual formula of a molecular compound
Molecular Formula
the mixing of orbitals or two or more orbitals of similar energies into orbitals of equal energy.
Hybridization
Compounds will _________ their molecular orbitals when bonding to form bonds that have specific angles. This will give that molecule a particular, identifiable shape that gives that compound its specific properties.
rearrange
forces other than bonds that are found between atoms
Intermolecular Forces
found between polar molecules only. They are short-range forces and their compounds usually have very high boiling points (ex. BrF)
Dipole-Dipole Forces
forms between hydrogen bond/force such as fluorine and oxygen. These compounds, like water, have very high boiling points.
Hydrogen Force
results from the constant motion of electrons that create an instantaneous dipole. These forces increase as the size of the compound increases. Br2 has greater forces than Cl2.
London Dispersion
a “bond” that occurs between metals only and is the result of the attraction of the protons in one atom for the electrons in another atom. This produces a “sea” of electrons around the alloy which allows that alloy to conduct an electrical current. It varies with the number of valence electrons in the “se” and the nuclear charge of the atom.
Metallic Bonds
the energy required to break a chemical bond. The more bonds found between two elements, the harder they are to break.
Bond Energy
Chemical compounds tend to form so that each atom, by gaining, losing, or sharing valence electrons, has an octet of electrons in its las (highest) energy level.
The Octet Rule
uses dots to symbolize the valence electrons in an atom. One pair of electrons is symbolized by one line. Two pair equals two lines.
Lewis Structures
states that the repulsion between the sets of pairs of valence electrons surrounding an atom can cause sets of electrons to be placed as far apart as possible. (remember Hund’s rule?)
VSEPR Theory (Valence-Shell Electron Pair Repulsion)
