Unit 1, covalent compounds

Question 1

Lewis structure

Answer 1

shows connectivity btwn atoms and their bond order (single, double, triple bond)
shows valence e not used for bonding
reflects central idea that stability of a compound relates to noble gas e configuration

Question 2

Octet Rule

Answer 2

elements form stable molecules when surrounded by 8 electrons

Question 3

Single covalent bond

Answer 3

a covalent bond in which 2 atoms share 1 pair of electrons

Question 3

double covalent bond

Answer 3

a covalent bond in which 2 atoms share 2 pairs of electrons

Question 4

triple covalent bond

Answer 4

a covalent bond in which 2 atoms share three pairs of electrons

Question 5

Steps for drawing lewis structures (6)

Answer 5

1. decide which atoms are bonded (least electronegative atoms is the central, except for hydrogen)
2. count ALL valence electrons
3. place 2 electrons in each bond
4. complete the octets of the atoms attached to the central atom by adding electrons in pairs
5. place any remaining electrons on the central atom in pairs
6. if the central atom does not have an octet, form double bonds, if necessary, form triple bonds

Question 6

Co-ordinate covalent bonds

Answer 6

when one atom contributes both electrons, ex ammonium

Question 7

Incomplete octet

Answer 7

central atom has fewer that 8 electrons (octet) around them in their compounds
H (2e), Be (4e)- acts covalent, B(6e)

Question 8

Exceeds octet

Answer 8

central atom CAN have greater that an octet of electrons
-feature of some period 3 and higher elements
-second row elements NEVER exceed octet
PAsSXeCl
P (10e), As (10e), S (12e), Xe (12e), Cl (14e)

Question 9

VSEPR

Answer 9

valence-shell electron-pair repulsion