CHEMICAL BONDS

CHEMICAL BONDING I

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 1 Level 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

IONIC BOND ELECTRONS ARE TRANSFERRED POSITIVE charge NEGATIVE charge

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 Na Sodium atom Cl Chlorine atom Na + Sodium ion Cl – Chloride ion Sodium chloride (NaCl) NaClNaCl + –

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

Sodium and chloride ions bond to form sodium chloride, common table salt Na + Cl –

CHEMICAL BONDING II

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

Molecules can be represented in many ways