Periodic table and molecules

Flame tests

Method used to identify the presence of certain metal ions based on the color of light emitted when heated.

Emission spectrum

A pattern of lines corresponding to different energy levels produced by electrons transitioning back to lower energy states.

Valence electrons

Electrons in the outer shell of an atom that are involved in chemical reactions.

Alkali metals

The most reactive metals in Group 1 of the periodic table, characterized by having one valence electron.

Alkaline earth metals

Group 2 metals that are very reactive and react strongly with water.

Transition metals

Elements found in the center of the periodic table, known for their ability to form various oxidation states.

Metalloids

Elements that have properties intermediate between metals and nonmetals, often found along the staircase line in the periodic table.

Nonmetals

Elements that are generally gases at room temperature, with Bromine as the only liquid nonmetal.

Halogens

Group 7 elements that react with metals to form salts.

Noble gases

Group 18 elements that are unreactive due to having a full valence shell.

Reactivity

A measure of how easily an element can give away an electron, increasing down a group and decreasing across a period.

Electronegativity

The ability of an atom to attract electrons, which decreases down a group and increases across a period.

Atomic Radius

The size of atoms measured by their radius, which increases down a group and decreases across a period.

Metallic Character

The tendency of metals to lose electrons; increases down a group and decreases across a period.

Ionisation energy

The amount of energy required to remove an electron from an atom to form an ion, highest in noble gases.

Ionic bonding

A chemical bond formed between metals and nonmetals through the transfer of electrons.

Cation

A positively charged ion that forms when a metal loses electrons.

Anion

A negatively charged ion that forms when a nonmetal gains electrons.

Sodium chloride

The result of ionic bonding between sodium and chlorine (NaCl).

Crystal lattice

A regular arrangement of alternating cations and anions in ionic compounds.

Polyatomic ions

Ions made up of two or more atoms that together have a charge.

Metallic bonding

Chemical bonding that results from the attraction between positively charged metal ions and delocalized electrons.

Alloys

Mixtures of two or more metals that have desirable properties.

Work hardening

Process of hardening metal through mechanical work, causing rearrangement of atoms.

Heat treatment

Controlled heating and cooling process to alter the properties of metals.

Annealing

Heating metal and slowly cooling it to make it softer and more ductile.

Quenching

Rapid cooling of heated metal, resulting in increased hardness but also brittleness.

Tempering

Process of reheating quenched metals to reduce brittleness and retain hardness.

Covalent bonds

Bonds formed when nonmetals share electrons to achieve full valence shells.

Intramolecular bonds

Strong forces of attraction that hold atoms together within a molecule.

Intermolecular bonds

Weaker forces of attraction between different molecules.

Bonding electrons

Electrons that are shared between atoms in a covalent bond.

Non-bonding electrons

Electrons in the outer shell that are not involved in bonding.

Lone pairs

Pairs of non-bonding electrons that can affect molecular shape.

Double bonds

Covalent bonds formed when two pairs of electrons are shared between atoms.

Triple bonds

Covalent bonds formed when three pairs of electrons are shared.

Valence Shell Electron Pair Repulsion (VSEPR)

Model used to predict the 3D shape of molecules based on electron pair repulsion.

Tetrahedral structure

A molecular shape with four bonding pairs arranged to minimize electron pair repulsion.

Trigonal Pyramidal

Molecular shape characterized by three bonding pairs and one lone pair.

V-Shaped (bent) structure

Molecular shape with two bonding pairs and two lone pairs.

Linear structure

Simplest molecular shape characterized by one bonding pair.

Trigonal planar

Molecular shape with three bonding pairs and no lone pairs, angles of 120 between bonds.