Chemistry Bonding Review

1. Ionic bonding: The transfer of electrons (metal/nonmetal) from one atom to another resulting in an electrostatic charge. (“One give, One take”) •

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Ion formation in metals: As atoms form ions, they result in the formation of ions with noble gas electron configuration. It then loses its valence electron from the atom’s outer energy level which results in the ions having a smaller radius than the atom from which it was formed. Ion formation in nonmetals: Gains enough electrons to satisfy the octet rule to form an ion. It results in the ion having a larger radius than the atom from which it was formed. ** Nonmetals gain electrons; metals lose electrons.

2. Covalent bonding: Occurs when two or more nonmetals share electrons, attempting to attain a stable octet of electrons. • •

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Nonpolar Covalent Bonds: attraction of the two element’s nuclei for the shared electron is equal, causing the pair of electrons to be shared equally. Polar covalent bonds: The unequal sharing of the sharing of electrons in the bond is unequal. The element with the higher electronegativity attracts the shared electron more strongly, causing that portion of the molecule to acquire a partially negative charge. Covalent bond: 1 pair or 2 electrons Double covalent bond: 2 pair or 4 electrons Triple covalent bond: 3 pair or 6 electrons Metallic bonding: Free flowing- sea of electrons attracted to the metal’s nucleus. (metals/metal)

The octet rule states that in order to form compounds, the atoms have to have the electron configuration of the noble gases. It explains why the noble gases nave no electronegativity because the noble gases are not “greedy” for anymore electrons. Every element wants to be like them, so they don’t want to add or remove any electrons.

Properties of Ionic Compounds • • • •

Brittle High melting points Dissolves in water When molten (turned into a liquid), it conducts electricity.

Properties of Covalent Compounds

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Soft Bad conductors of heat and electricity Low meting points

Properties of Metallic Compounds • •

Hard Good conductors of heat and electricity

Molecule: two or more atoms combined (bonded) covalently. Chemical bond: An attraction between atoms or molecules that allows the formation of chemical compounds, which contain two or more atoms. The attraction is caused by the electromagnetic force between opposing charges as a result of a dipole attraction. Coordinate covalent bond: A covalent bond in which one atom contributes both of the bonding electron. Diatomic: Two atoms. •

H2, O2, F2, Br2, I2, N2, Cl2

Allotrope: Two different structures of the same element with different properties. Binary Compound: Two different elements. Can be ionic or covalent. •

Ex. H2O, CaCl2

Monatomic ion: One atom and an ion •

Ex: Fl-

Polyatomic ion: ions that consist of more than one atom. •

Mg2+

Polarity • •

When one atom is significantly more electronegative than another, giving that atom a slight negative charge and the other atom a slight positive charge. A polar molecule has one end with a positive charge and another end with a negative charge.

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It is non-polar when both atoms exert an approximately equal pull on the electrons in the bond. Difference in electronegativity is less than 0.4: Non- polar Difference in electronegativity is more than 0.4: Polar

**The symmetrical molecules are nonpolar, the asymmetrical molecules are polar.

Dipoles: Polar molecules. (Has the prefix di- because they have two charged ends.) • •

The shape of a molecule and the polarity of its bonds together determine whether the molecule is polar or non polar. You can signify the polarity of a bond with an arrow. By combining the arrows for each bond, you can determine the polarity of the molecule.

** You can draw arrows from the less electronegative element to the more electronegative element to indicate the pull of electrons. By examining the arrows you can tell if the forces cancel each other out resulting in a non polar molecule or if they do not cancel resulting in a polar molecule.

Water • •

Water is a polar molecule because of its bent shape. The polarities of the 2 hydrogen-oxygen bonds are signified by arrows of the same magnitude, but these arrows do not point in opposite directions.

Intermolecular Forces: the forces of attraction between neighboring molecules. Three forces of attraction between molecules: • •

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Dispersion/ Van der Waals forces: Weak attraction between non polar molecules. The forces get stronger as the molecule get heavier. Diplole-dipole forces: Polar molecules have a small positive charge at the end of the molecule and an equal negative charge at the other end. Attractions between opposite charges of neighboring permanent dipoles. Hydrogen bonding: occurs when hydrogen bonds with F, O or N. The bonds are very polar and the atoms are small.

Molecule- Ion Attraction: ionic compound in water.

NaCl+H2O

Na+ (aq)Cl+(aq)

Rules for naming compounds: Binary ionic compound • • •

Two elements The cation (+) always comes first with its full name. The anion (-) is second and changes the ending to –ide.

Ex. Magnesium Chloride- MgCl2; Calcium Nitrate- Ca3N2

Binary Covalent Compound • • • •

Two elements The second atom ends in –ide. Use prefixes to determine the number of atoms. Don’t use mono for the first atom. The less electronegative atom usually comes first.

Ex. CCl4- Carbon Tetrachloride; N2O5- Di-nitrogen Penta-oxide

Transition Metals • •

Can give away varying numbers of electrons. Roman numeral tells you the charge on the transition metal.

Ex. PbO- Lead (II) Oxide; SnO2- Tin (IV) oxide

Polyatomic Ions •

Use “Table E” on the Reference Table.

Ex. NH4OH- Ammonium Hydroxide; KMnO4- Potassium Permanganate

**It takes energy to break bonds (absorbs energy). Energy is released when a bond forms (gives energy).