CHEM 110 Chapter Notes - Chapter 3: Features Of The Marvel Universe, Benzene, Nitric Acid
10 May 2018
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Chapter 3 Molecules, Compounds & Nomenclature
Hydrogen, Oxygen, & Water
- Hydrogen is an explosive Gas
- Oxygen is a natural component of air on the earth
o Hydrogen & Oxygen have low boiling points
o When hydrogen and oxygen combine to form H2O, a different substance is
created (Water)
▪ Its boiling point is hundreds of degrees above boiling points of hydrogen
& oxygen
▪ Water smothers flames
- When two elements combine to form a compound, an entirely new substance is created
Chemical Bonds
- Chemical bonds hold together atoms within a compound
o Result of interactions between charged particle (Electron/Proton)
o Atoms with 8 electrons in the outer shell are chemically stable (Octet Rule)
▪ Tendency of atoms to prefer 8 electrons
- Chemical bonds are classified into two types
o Ionic
▪ Metals & Non-Metals
▪ Transfer of electrons from one atom to another
o Covalent
▪ Two or more non-metals
▪ Sharing of electrons between two atoms
- Ionic Bonds
o When a metal interacts with a non-mental, it can transfer one of the electrons to
the non-metal
o Metal atom becomes a cation (Positively charged ion) and the non-metal becomes
a anion (negatively charged ion)
o These oppositely charged ions are attracted and form an ionic bond
- Covalent Bonds
o When a non-metal bonds with another nonmetal, neither atoms transfer, instead
they are shared
▪ Lowering the potential energy
o Result is a molecular compound, composed of covalently bonded molecules
Representing Compounds: Formulas and Molecular Models
- Chemical Formulas can be categorized as one of three types
o Empirical
▪ Gives relative number of atoms each element in a compound
▪ Able to observe the ratio of the elements in the molecule
▪ Example: Hydrogen Peroxide (HO)
o Molecular
▪ Gives actual number of atoms of each element in a molecule of a
compound
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▪ Hydrogen Peroxide (H2O2)
o Structural
▪ Uses Lines to represent covalent bonds to show hoe atoms in a molecule
are connected
▪ H2O2 = H:O:H:O
▪ Example: O═C═O
• The two lines represent a double bond
o Two shared electrons are paired
- Atomic
Elements
o Exist in nature with single atoms as base unit
- Molecular elements
o Exist as molecules
o Two or more atoms of the element covalently bonded together
o Diatomic molecules
▪ Hydrogen (H2)
▪ Nitrogen (N2)
▪ Oxygen, Fluorine, Chlorine, Bromine, Iodine
- Molecular Compound
o Two or more covalently bonded non-metals
▪ H2O
▪ C3H8 (Dry Ice)
- Ionic Compounds
o Composed of cations and anions bounded by a ionic bond
▪ NaCl is composed of Na+ & Cl-
o Polyatomic Ion (Composed of two or more a\ covalently bonded non-metals with
a charge) NO3-
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Formul as and Names
- Common Names
o Traditional name of a compound that gives little or no information about its
structure
- Systematic Names
o Official name for a compound that can be determined by examining its structure
- Ionic Compound formulas (Metals & Non-Metals)
o Ionic compounds always contain positive and negative ions
o The sum of positive ions (cations) must equal the sum of negative ions (anions)
o Formula reflects the smallest whole number ratio of ions
o Procedure:
▪ Write the symbol for the metal cation & charge followed by non-metal
anion & charge
▪ Adjust subscript on each cation & anion to balance overall charge
▪ Check the sum of cations to see if it equal sum of anions
• Example: Potassium Nitride
o K+ & N3-
o K3N
o (Need 3 Potassium to balance the Nitrogen)
• Example: Aluminum Oxide
o Al3+ & O2-
o Al2O3
o (Need 3 Oxygen to balance the 2 Aluminum)
o The name of the ionic compound is the name of the cation followed by the anion
o If there are only two ions in the series, the one with more oxygen atoms has the
ending –ate and the one with fewer has the ending –ite.
o If there are more than two ions in the series, the prefixes hypo-, meaning less
than, and per–, meaning more than
- Polyatomic Ions Formula
o Find the charge for both to find the formula
▪ Example: Calcium Nitrate
• Ca2+ & NO3-
o There are 2+ of calcium and 1- of Nitrate
o Must Balance
▪ Add a 2nd Nitrate to have 2- to balance the 2+ of
calcium
o Ca(NO3)2
▪ Parenthaese indicate how many of the element
▪ Example: Ammonium Nitride
• NH4+ & N3-
o There are 3- of Nitride and 1+ of Ammonium
o Must Balance
▪ Add 3 Ammonium to balance the 3- of Nitride
o (NH4)3N
▪ Example: Sodium Carbonate
• Na+ & CO32-
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Document Summary
Oxygen is a natural component of air on the earth: hydrogen & oxygen have low boiling points, when hydrogen and oxygen combine to form h2o, a different substance is created (water) Its boiling point is hundreds of degrees above boiling points of hydrogen. When two elements combine to form a compound, an entirely new substance is created. Chemical bonds hold together atoms within a compound: result of interactions between charged particle (electron/proton, atoms with 8 electrons in the outer shell are chemically stable (octet rule, tendency of atoms to prefer 8 electrons. Chemical bonds are classified into two types: ionic, metals & non-metals, transfer of electrons from one atom to another, covalent, two or more non-metals, sharing of electrons between two atoms. Covalent bonds: when a non-metal bonds with another nonmetal, neither atoms transfer, instead they are shared, lowering the potential energy, result is a molecular compound, composed of covalently bonded molecules.
