CHEM EXAM 10TH GRADE

Valence Electrons

Electrons in an atom's outer shell that determine its bonding behavior.

Octet Rule

Atoms tend to bond in a way that results in eight valence electrons in their outer shell for stability.

Cation

A positively charged ion formed when a metal loses electrons.

Anion

A negatively charged ion formed when a nonmetal gains electrons.

Lattice

A large group structure formed by the attraction of anions and cations in ionic compounds.

Covalent Bond

A bond formed by sharing a pair of electrons between two non-metal atoms.

Dative Covalent Bond

A type of covalent bond where both bonding electrons come from one atom.

Diatomic Molecules

Molecules made up of two atoms of the same or different elements joined by covalent bonds.

Law of Conservation of Mass

The principle that mass is neither created nor destroyed during a chemical reaction.

Enthalpy Change (ΔH)

The change in heat energy during a chemical reaction transferred between the system and surroundings.

Exothermic Reaction

A reaction that releases energy to the surroundings, resulting in an increase in temperature.

Endothermic Reaction

A reaction that absorbs energy from the surroundings, resulting in a decrease in temperature.

Activation Energy (Ea)

The minimum energy required for reactants to form products.

Bond Enthalpy

The energy required to break one mole of chemical bonds in gaseous state.

Calorimetry

A technique used to measure the heat transfer during a process.

Q=mcΔT

Formula to calculate thermal energy, where Q is thermal energy, m is mass, c is specific heat capacity, and ΔT is change in temperature.

Energy Profile Diagram

A graphical representation of the potential energy changes throughout a chemical reaction.

LOL Diagrams

Energy bar charts that model energy transfer in terms of thermal, phase, and chemical energy.