All Things Covalent

Atom in the center of the lewis structure, forms most bonds, is the least EN (NEVER H)

USUALLY the first element listed in the chemical formula OR look for least EN

exceptions:

- diatomic compounds (2 atoms)

-Hydrogen is the starting element

Bonding sites & if you count them up the ideal # of bonds

NO, NEVER.

FC= VE-CB-NE

The # of valence electrons (from periodic table) - # of covalent bonds on the atom (on the LS) - # of non-bonded e- (on the LS)

-Do this for each atom in the compound and then add up their charges to see the compounds overall charge

-Most stable is zero UNLESS it’s a polyatomic in which case it would be the charge of the polyatomic that is most stable

Polyatomic’s have both ionic and covalent character (covalently bonded cluster of atoms with an ionic charge)

Put the compound in parentheses and put the charge on it’s upper right corner

Conductive

this is bc the transfer of e- is quicker & more efficient

Resonance structures show the multiple ways bonding can occur in a compound

They are caused when there is more than one way to place double bonds and lone pairs on atoms

When both bonding e- are donated by a single atom

ie. this happens when one atom is satisfied and another isn’t, the satisfied atom will share 2 of it’s e with the other atom, forming a bond, to satisfy it so the whole compound can be more stable

Double or Triple bonds

-these occur to satisfy atoms that do not fulfill the octet rule

The D sub-level acts like a trunk where extra e- can be stored if need be, this is why we can fit 10 e- on some atoms instead of only eight, bc 2 would be in the “trunk”

The bonds are SPD hybrids when this happens

12*

*only when acting as a central atom!

10*

*only when acting as a central atom!

2

6*

*only when acting as a central atom!

4*

*only when acting as a central atom!

*Note, this is a metal but it’s EN is close to NM so it can covalently bond

Atoms that are stable with less than 8 e-

These are H, B, Be

Atoms that can hold 8+ e- but can be stable @ 8

These are P, S, Noble gases & Halogens (NG and Halogens are VERY rare)

Bc they do not have charged particles capable of transporting e-

Molar mass

more mass= more substance to melt

Can be solid, liquid, or gas

Bc they have weak forces of attraction btwn them. Since covalent bonds form btwn NM’s there is no opposite charges & therefore no coulombic attraction, this makes the force weaker. The e- are also shared, not transferred, making a weaker bond which is easier to break and therefore a lower MP/BP

-low melting/boiling point

-soluble (dissociates in water)

-non-conductive

-share e- to achieve octet

Covalent bonds share e- via. orbital overlap

-more overlap (ie. double & triple bonding) = stonger bond

They can act like noble gases (and be stable)

Molecule

Non-metals only*

They share electrons

*Some metalloids bond with nonmetals and tend to form covalent bonds

pair of e- that are NOT shared btwn atoms

ONLY on the central atom