Post on 02-Jan-2016
Constructing Molecular Models
What limited the number of “atoms” you could connect?
Black – 4, Red – 2, White - 1
Energy levels (valence levels)
Level 1: ___ electrons
Level 2: ___ electrons
Level 3: ___ electrons
This energy level can hold __ more electrons
Level 1Level 2
How many more electrons can this atom hold? ______
Is it easier to lose 1 electron, or gain 7?
The third level can hold up to 18 electrons.
What is happening here?
The Na atom is ________________ an electron and the Cl atom is ______________ an electron.
The Na atom becomes _______ charged, the Cl atom becomes _____ charged.
They are attracted to each other and form a bond.
• Atoms whose shells are not full tend to interact with other atoms and gain, lose, or share electrons
HYDROGEN (H)Atomic number = 1
CARBON (C)Atomic number = 6
NITROGEN (N)Atomic number = 7
OXYGEN (O)Atomic number = 8
Electron
Outermost electron shell (can hold 8 electrons)
First electron shell (can hold 2 electrons)
Empty spaces
• When atoms gain or lose electrons, charged atoms called ________ are created– An electrical attraction between ions with opposite
charges results in an ___________ bond
Ionic bonds are attractions between ions of opposite charge
NaSodium atom
ClChlorine atom
Na+
Sodium ionCl–
Chloride ion
Sodium chloride (NaCl)
Na Cl Na Cl
+ –
Ionic Bonds• Form when 1 or 2 electrons are
transferred from one atom to another
• This creates an attraction between the two atoms – holds them together
• One becomes a __________ ion and the another _____________ ion
• ________ bond - Dissolves easily in water, usually
Covalent bonds
are created when atoms ___________
electrons.
Electrons are shared!
How many more electrons can these atoms hold?
_______
• Some atoms SHARE outer shell electrons with other atoms, forming __________ bonds– Atoms joined together by covalent bonds
form molecules
– Very ________ bond
Covalent bonds, the sharing of electrons, join atoms into
molecules