Chemical Bonding

types of bonds

ionic, covalent and metallic bonding

ionic bond (definition)

bond formed when one or more electrons are transfered from one atom to another

ionic bond (description)

a chemical bond resulting from the attraction between oppositely charged ions.

ionic bond (types of elements)

metals with nonmetals

ionic bond (nature of)

electrostatic attraction

ionic compounds (properties)

1. crystalline solids

2. high melting and boiling point

3. electrolytes

4. soluble in water (usually)

how are ionic compounds electrically neutral?

the positive and negative charges balance out (cancel out)

coulombic attraction

the attraction between oppositely charged particles

metals in ionic bonds

few valence electrons - tend to lose them - for positive ions

cation

a positively charged ion

nonmetals in ionic bonds

many valence electrons - gain a few - form negative ions

anion

a negatively charged ion

group 1A (charge formed)

1+

group 2A (charge formed)

2+

group 7A (charge formed)

1-

group 6A (charged formed)

2-

formula unit

smallest unit of an ionic compound

electrolyte

substance that forms ion when it is dissolved in water, capable of conducting an electrical current

isoelectronic

having the same electron configuration as another species

metallic bond (definition)

a bond formed by the attraction between positively charged metal ions and the electrons around them

metallic bond (model)

mobile electrons are delocalized and form a "sea of electrons" around metal atoms

alloy (definition)

a mixture of two or more elements, one of which is a metal

alloy (examples)

Sterling silver, Bronze, Brass and Steel

sterling silver

silver alloyed with copper

bronze

copper alloyed with tin

brass

copper alloyed with zinc

steel

iron alloyed with small amounts of carbon

covalent bond (definition)

a chemical bond that involves sharing a pair of electrons between atoms in a molecule

covalent bond (types of elements)

two or more nonmetals

covalent bond (aka)

molecular bond (aka)

molecular compounds (properties)

1. can be solid, liquids or gases

2. lower melting and boiling points

3. not electrolytes

molecule

smallest unit of a covalent compound, two or more atoms held together by covalent bonds

single bond

a covalent bond in which two atoms share one pair of electrons

double bond

a covalent bond in which two atoms share two pairs of electrons

triple bond

a covalent bond in which two atoms share three pairs of electrons

coordinate covalent bond

a covalent bond in which one atom contributes both bonding electrons

polar covalent bond

a covalent bond in which electrons are not shared equally

electronegativity

The ability of an atom to attract electrons when the atom is in a compound

diatomic molecule (definition)

a molecule that consists of two atoms of the same element when in the free state

diatomic molecule (elements)

N₂,O₂,F₂,Cl₂, Br₂, I₂, H₂

octet rule

atoms react by gaining or losing electrons so as to acquire the stable electron structure of a noble gas, usually eight valence electrons

molecular orbitals

an orbital resulting from an overlapping of atomic orbitals when two atoms combine

sigma bond (definition)

covalent bonds formed by orbitals overlapping end-to-end, with the electron density concentrated between the nuclei of the bonding atoms

sigma bond (description)

overlap of two S orbitals, 2 P orbitals (end-to end), or a S and P orbital

-represents the sharing of one pair of electrons (single bond)

pi bond (definition)

a bond that is formed when parallel orbitals overlap to share electrons

pi bond (description)

A bond formed when parallel p orbitals overlap creating two regions of electron density, one above and one below the internuclear axis.

VSEPR stands for?

Valence Shell Electron Pair Repulsion Theory

VSEPR Theory

the repulsion between electron pairs causes molecular shapes to adjust so that the valence electron pairs stay as far apart as possible

list these in order of increasing polarity

HF, HI, HBr, HCl

HI, HBr, HCl, HF

factors contributing to molecular polarity

1. bond polarity

2. molecular shape

shape of water molecule

coordinate covalent bond (diagram)

single bond (example)

double bond (example)

triple bond (example)

sp³ hybrid bond

...hybrid bond type?

sp² hybrid bond

...hybrid bond type?

sp hybrid bond

...hybrid bond type?

sigma bond (diagram)

...

pi bond (diagram)

...

bond dissociation energy

energy required to break a covalent bond - the higher the BDE the stronger the bond

resonance

alternate bonding for the same molecule

linear molecules

two or three atoms - bond angle 180° - ex: HCl, CO₂, CO

bent molecules

three atoms - bond angle 109° - ex: H₂O, H₂S

trigonal planar

four atoms - bond angle 120° - BF₃

trigonal pyramidal

four atoms - bond angle 109° - ex: NH₃, NF₃

tetrahdral

five atoms - bond angle 109° - CH₄, CCl₄