POLARITY OF MOLECULES

ATOM

SMALLEST UNIT of an ELEMENT that retains its CHEMICAL PROPERTIES; made of ELECTRON, PROTON, and NEUTRON

NUCLEONS

Refers to PROTONS (p⁺) and NEUTRONS (n⁰)

PROTON = ELECTRON

In a neutral atom, NUMBER of PROTONS equals ELECTRONS

NEUTRON

CALCULATED as ATOMIC MASS minus PROTONS

MOLECULE

COMBINATION of TWO or MORE ATOMS held by CHEMICAL BONDS; smallest PARTICLE of a COMPOUND that retains PROPERTIES

DIATOMIC MOLECULE

MOLECULE composed of TWO ATOMS

POLYATOMIC MOLECULE

MOLECULE composed of MORE THAN TWO ATOMS

CHEMICAL BONDING

ATTRACTION or FORCE that holds TWO ELEMENTS TOGETHER by SHARING or TRANSFERRING ELECTRONS to become STABLE

IONIC BOND

TRANSFER of ELECTRONS between METAL and NON-METAL (e.g., NaCl)

COVALENT BOND

SHARING of ELECTRONS between NON-METALS (e.g., CO₂, H₂O)

METALLIC BOND

METAL ATOMS share a CLOUD OF ELECTRONS (e.g., Zn⁺)

POLAR COVALENT BOND

UNEQUAL SHARING of ELECTRONS due to DIFFERENT ELECTRONEGATIVITY

NONPOLAR COVALENT BOND

EQUAL SHARING of ELECTRONS between ATOMS with SIMILAR ELECTRONEGATIVITY

ELECTRONEGATIVITY

Ability of an ATOM to ATTRACT ELECTRONS during CHEMICAL BONDING

LEWIS DOT STRUCTURE

VISUAL REPRESENTATION of VALENCE ELECTRONS and BONDING in MOLECULES

VALENCE ELECTRONS

ELECTRONS in the OUTERMOST SHELL of an ATOM

CENTRAL ATOM

ATOM with the LEAST NUMBER of ATOMS AROUND IT; placed in the CENTER in Lewis Structures

SINGLE BOND

ONE PAIR of SHARED ELECTRONS; shown as ONE LINE "-"

DOUBLE BOND

TWO PAIRS of SHARED ELECTRONS = 4 ELECTRONS

TRIPLE BOND

THREE PAIRS of SHARED ELECTRONS = 6 ELECTRONS

LONE PAIRS

ELECTRONS NOT SHARED with another ATOM

OCTET RULE

Most ATOMS aim to have 8 ELECTRONS in their VALENCE SHELL (HYDROGEN = 2)

POLARITY BY STRUCTURE

POLAR if DIPOLE ARROWS point to CENTRAL ATOM; NONPOLAR if SYMMETRIC and NO LONE PAIRS

DETERMINING POLARITY

Draw LEWIS STRUCTURE, calculate EN DIFFERENCE; if

SOLUBILITY RULE

LIKE DISSOLVES LIKE: POLAR dissolves in POLAR, NONPOLAR dissolves in NONPOLAR

MELTING POINT

TEMPERATURE where a SUBSTANCE TURNS from SOLID to LIQUID

BOILING POINT

TEMPERATURE where a SUBSTANCE TURNS from LIQUID to GAS

HYDROGEN BOND

STRONG INTERMOLECULAR FORCE usually in POLAR MOLECULES; raises MELTING and BOILING POINTS

LEWIS STRUCTURE STEPS

COUNT VALENCE ELECTRONS
IDENTIFY CENTRAL ATOM
DRAW SINGLE BONDS
ADD LONE PAIRS
FORM DOUBLE/TRIPLE BONDS for OCTET