Atoms, Electronegativity, Acids, and Bases Overview

Atoms

Fundamental unit of all matter

Protons

(+) positively charged particles

Neutrons

Uncharged particles

Electrons

Negatively charged particles

Nucleus

Middle of atom where protons and neutrons are located

Mass

# of protons + # of neutrons

Electron shells

Shells of electrons surrounding the nucleus

First shell

Can hold two electrons

Next shell

Can hold 8 electrons

Valence Shell

The outermost shell of an atom

Oxygen protons and electrons

Oxygen has 8 protons and electrons (combined)

Oxygen valence electrons

6 because 2 electrons have filled the first shell, the other 6 will be on the next outermost shell

Full valence shell for oxygen

Oxygen would need 2 more electrons to have a full valence shell

Molecule

Atoms bond together and form specific types of bonds called a Covalent Bond (electron-sharing bond)

Covalent Bonds

The number of covalent bonds atoms can form is based on the number of empty spots they have in their valence shell.

Oxygen

Oxygen can form 2 covalent bonds.

Hydrogen

Hydrogen can form 1 covalent bond.

Carbon

Carbon can form 4 covalent bonds.

Nitrogen

Nitrogen can form 3 covalent bonds.

Electronegativity

The propensity of an atom to attract electrons.

Electronegativity Determinants

Electronegativity is determined by the number of protons and the distance of the valence electrons from the nucleus.

Fluoride

Fluoride is the most electronegative element due to its position in the periodic table, far up and far right.

Electronegativity of Carbon

Carbon has an electronegativity of 2.55.

Electronegativity of Hydrogen

Hydrogen has an electronegativity of 2.20.

Electronegativity of Nitrogen

Nitrogen has an electronegativity of 3.04.

Electronegativity of Oxygen

Oxygen has an electronegativity of 3.44.

Non-Polar Bonds

If two atoms have the same or approximately the same electronegativity, the bond is non-polar.

Polar Bonds

If electrons are shared unevenly, the bond is polar.

Hydrogen Bonds

An attraction between a partial negative on one molecule and a partial positive on another molecule or another region of the same molecule.

Strong Acid

A substance that fully dissociates in water, such as HCl, H2SO4, and HNO3.

H^+ Ion

An H^+ ion has one more proton than it has electrons, thus it is a proton.

Weak Acids

Weak acids do not fully dissociate in water and some amount stays together.

Acid Strength

The strength of an acid is related to how much of the molecule is in the dissociated state.

Organic Acids

Organic acids commonly have a COOH group.

Bases

A substance that reduces the concentration of hydrogen ions in a solution.

pH Scale

The pH scale describes the concentration of hydrogen ions, calculated as Negative Log of [H^+].

pH Relationship

If [H^+] = 10^-7, then pH = 7; lower pH means more hydrogen ions, higher pH means less hydrogen ions.