Chapter 5: electrons and bonding

Shell

a group of atomic orbitals with the same principle quantum number

Number of electrons held by each shell

2n²

Where n is the shell number

atomic orbital

a region around the nucleus that can hold up to 2 electrons with opposite spins

shape of s orbital

spherical

how many s orbitals does a shell contain

1

shape of p orbitals

3d dumbbell

which shells contain p orbitals and how many do they contain?

every shell from the 2nd shell has 3 p orbitals at right angles to each other

shape of d orbitals

more complex shape

which shells contain d orbitals and how many do they contain?

Each shell from the 3rd shell contains 5 d orbitals

Why does the 4s shell fill before the 3d in Cu and Cr?

enhanced stability of full/half full sub shell

ionic bonding

the electrostatic attraction between oppositely charged ions

melting and boiling points of ionic sunbstances

high due to a large quantity of energy required to overcome strong electrostatic bonds

how does ion size affect boiling/melting points?

the bigger the ion size, the lower the melting/boiling point due to the outer shell being further from the nucleus (thus decreasing the electrostatic attraction)

how does ion charge affect melting/boiling points?

as ion charge increases, the boiling/melting points increase due to greater electrostatic attraction

Conditions for a substance to dissolve

the ionic lattice has to break down

Water molecules must be attracted to the ions and surround them

The attraction between the water and individuals ions should be greater than the electrostatic attraction between oppositely charged ions

covalent bond

the strong electrostatic attraction between a negatively charged shared pair of electrons and the positive nuclei of the bonded atoms

when are covalent bonds formed?

when the orbitals of the bonded atoms overlap

octet rule

in most covalent substances, the central atom will bond so that its outer shell has four pairs of electrons

exceptions to the octet rule

BF₃

SF₆

dative covalent (coordinate) bonding

a type of covalent bonding where both electrons in the shared pair are donated by one atom

average bond enthalpy

the energy required to break 1 mole of a specified type of bond in a gaseous molecule