Honors Chemistry Final

Ions

An ion is formed when an atom gains or loses electrons, resulting in an overall positive or negative charge.

If an atom loses electrons, it has more protons than electrons and become a positively charged ion (called a cation)

If an atom gains electrons, it has more electrons than protons and becomes a negatively charged ion (called anion)

Naming Ions

Cations (typically formed by metals) is the name of the element when usually unchanged. Na to Na*

Anions (typically formed by non-metals) are the ending of the elements name is changed to “-ide”. Chloride atom (Cl) to Chloride ion (Cl^-)

Naming Ionic Compounds

The name of the metal (cation) is written first

The name of the non-metal (anion) I written second, with its ending changed to “ide”

EX: NaCl is sodium chloride. MgO is magnesium oxide

If its a transition metal, us roman numerals to show the charge, Copper II.

Naming Acids

-Naming Rules based on the anion: If the anion’s name ends in “ide”

Begin the acid name with the prefix “hydro-”

Change the anion’s “ide” ending to “-ic acid”

EX: HCl (anion is chloride, Cl) → hydrochloric acid

-If the anion is a polyatomic ion it ends in “ate”

Change the anion’s ate” ending to “ic acid” (with no hydro)

EX: H₂SO₄ (anion is sulfate, SO₄²) → Sulfuric acid

-If the anion is polyatomic ion that ends in “-ite”

Change the anion’s “ite” to “ous acid” (with no hydro)

EX: H₂SO₃ (anion is sulfite, SO₃^2-) →Sulfurous acid

Covalent Bonding

Naming them: first element is its full name and the second element is named as if it were an anion (ending in “ide) CO₂- Carbon dioxide

Lewis Dot Diagram: Diagrams that represent the valence electrons of atoms and how they are shared in a molecule or polyatomic ion.

A pair is called covalent bond

Non-Bonding electrons (or lone pairs): Valence electrons that are not involved in bonding and belong to a single atom.

The “octet rule stated that atoms tend to bound in such a way that they each have eighteen electrons in their valence shell (but hydrogen only has 2)

Molecular Shapes/Molecular Geometry (VSEPR Theory)

The Valence Shell Electron Repulsion theory states that pairs of electrons (both bonding pairs and lone pairs) in the valence Shell of a central atom repel each other and will arrange themselves to be as far apart as possible. This arrangement determines the molecule’s 3D shape.

Common Molecular Shapes

Linear: 2 electrons domains around the central atom, 0 lone pairs, Bond angle - 180

Trigonal Planar: 3 Electron domains, 0 lone pairs, Bond angle - 120

Tetrahedral: 4 Electron domains, 0 lone pairs, Bond angle - ~109.5

Trigonal Pyramidal: 4 Electron domains, 1 lone pair (e.g. NH₃) Bond angle - <109.5 (approx. 107) + Lone pairs occupy more space than bonding pairs

Bent (or Angular): 4 electron domains, 2 lone pairs (e.g. H₂O) Bond angle - <109.5 (approx. 104.5) or 3 electron domains, 1 lone pair (e.g. SO₂) Bond angle - <120

Polar and Non-polar Molecules

Polar: Unequal charging of electrons - one end more negative then the other

Non-polar: Equal sharing of electrons - no charge separation

Symmetry = Non-polar, Asymmetry = Polar (SNAP)

Electronegativity: A measure of an atom’s ability to attract shared electrons in a covalent bond.

Polar Bond: A covalent bond in which electrons are shared unequally due to a difference in electronegativity between the two atoms. This created a bond dipole, with a partial negative charge on the more electronegative atom and a partial positive charge on the less electronegativity atom.

Non-polar Bond: A covalent bond in which electrons are shared equally, either because the atoms are identical (e.g. O₂, N₂) or very similar electronegativities.

Intermolecular Forces (IMFs)

Attractions between separate molecules

IMFs influence physical properties like boiling points, melting points, and viscosity.

Two types are

London Dispersion Forces (LDFs): Present in all atoms and molecules (both polar and non-polar) Result from temporary, instantaneous dipoles created by the random movement of electrons within an atom or molecule. Thee temporary dipoles can induce dipoles in neighboring molecules, leading to weak attractions. LDFs are stronger for larger molecules ( more electrons and larger electrons cloud)

Dipole-Dipole Forces: Occur between polar molecules. These forced are the attraction between he permanent positive end of one polar molecules and the permanent negative end of another. Stronger than LDFs for molecules of comparable size.

Organic Molecules & Functional Groups

Organic Molecules : Compounds primarily composed of carbon (C) and hydrogen (H). Carbon’s ability to form four covalent bonds allows for a vast array of chains, branches, and ring structure.

Functional Groups: Specific groups of atoms within an organic molecule that are responsible for the characteristic chemical reactions and properties of that molecule.

Bonding Properties

Chemical Reactions

Format: Reactant →Product

The → signifies “yeilds” pr “reacts to form”

EX: 2 H₂(g) + O₂(g) →2 H₂O(l)

(s)-solid (l)-liquid (g)-gas (aq)-aqueous (dissolved in water)

Chemical Equation Calculations (Stoichiometry)

Percent Yield

Theoretical Yield: The maximum amount of product that can be produced from a given amount of limiting reactant, calculated using stoichiometry.

Actual Yield: The amount of product actually obtained when the reaction is performed in a laboratory. This is an experimental value.

Percent Yield Formula: Percent Yield = (Actual Yield/ Theoretical Yield) x 100%

Solution Formulas

Concentration: Moles of solute/Liters of solvent

Dilution: M₁V₁ (volume MUST be the same units)

Titration: 1. Balance the equation 2. Find moles of titrant using M x V (Liters)

3. Find moles of analyte with Moles of titrant x coefficient analyte/ coefficient titrant (Mole ratio)

4. Molarity - Moles analyte/ Liters analyte