Download - Molecular Compounds
Molecular CompoundsMolecular Compounds
Learning Goal:
• Students will be able to name, draw and determine the formula of compounds
Agenda:• Ionic Compound Quiz• Yesterday’s work – problems?• Molecular Compounds • Practice time…
• Ionic CompoundsIonic Compoundsmetal + non-metal compoundmetals lose electrons to non-metalsmade of ions of opposite charges
Polyatomic Compounds
• Polyatomic Ion: An ion formed by a group of atoms with a shared charge
• Found in lots of everyday • Substances
• Copy the chart from p.182
Polyatomic Compouds
• Naming:– Name of positive ion first and polyatomic ion
second• Formulas:
– Use the crisscross method as before– Treat the polyatomic ion as one unit– Keep the polyatomic ion in brackets if there is a
number behind it
• Covalent BondsCovalent Bondsa shared pair of electrons between two non-
metal atomsatoms share electrons to form a stable
arrangement (like the noble gases)It’s like tug of war for the electrons that no
atom wins thus they “Share”
Molecule: a particle in which atoms are joined by covalent bonds
ExampleExample
• Ammonia – NH3
Ionic vs CovalentIonic vs Covalent
• Diatomic MoleculeDiatomic Moleculemolecule made of two atomsexample: H2
Elements that Form Diatomic MoleculesElements that Form Diatomic Molecules
Name of Element FormulaHydrogen H2
Oxygen O2
Nitrogen N2
Fluorine F2
Chlorine Cl2Bromine Br2
Iodide I2
Where We Find Molecular Where We Find Molecular Compounds?Compounds?
• molecular compounds are all around us• molecular compounds are found in water,
sugar, and molecules that provide flavour and colourexample: can of pop
Combining CapacityCombining Capacity• Combining capacity is the number of
electrons an atom can gain, lose, or share to form a stable molecule.
• Example: Oxygen has a combining capacity of 2.
Writing Formulas for Molecular Writing Formulas for Molecular CompoundsCompounds
• Write the symbols with combining capacities (element farthest left first)
• Crisscross the combining capacities• Reduce subscripts if possible
Example: carbon & sulfur C4 S2
C2S4
CS2 – carbon disulfide
Naming Molecular CompoundsNaming Molecular Compounds
1) Some molecular compounds are named the same way as IONIC COMPOUNDS. Ex. H2S is Hydrogen Sulfide
Naming Molecular CompoundsNaming Molecular Compounds
2) Many molecular compounds have COMMON NAMES. (Know these) Water (H2O) Ozone (O3) Ammonia (NH3) Hydrogen peroxide (H2O2) Methane (CH4)
3) PREFIXES are another method used to name molecular compounds.Prefixes are used to count the number of
atoms present in the compound.If there is only one atom in the first element in
the molecular compound, the prefix “mono” is not used.
• Examples:Carbon monoxide – COCarbon dioxide – CO2
Prefixes in Molecular CompoundsPrefixes in Molecular CompoundsPrefix Number Example
Mon(o) 1 Carbon monoxide (CO)
Di 2 Carbon disulfide (CS2)
Tri 3 Sulfur trioxide (SO3)
Tetra 4 Carbon tetrafluoride (CF4)
Pent(a) 5 d
Hexa 6