SAAT Chemistry Section 3 (Chemical Bonding and Intermolecular Forces of Attraction) - تحصيلي

Ionic bond

The electrostatic force that holds oppositely charged ions together

Ion

An atom or a particle that has a positive (cation) or a negative (anion) charge

The natural atom has

An equal number of protons and electrons

Crystal lattice

Three-dimensional geometric arrangement of particles formed by the strong attraction among the positive ions and the negative ions in an ionic compound

Ionic compounds can conduct electricity if

They were in a solution or a molten form

Melting point and boiling point

Very high in ionic compounds because it’s a very strong bond

Electrolyte

An ionic compound whose aqueous solution conducts an electric current

Lattice energy

The energy required to separate 1 mol of the ions of an ionic compound

Lattice energy is directly related to the size

Of the ions bonded

The ionic bond formed from the attraction of ions with larger positive or negative charges generally

Has a greater lattice energy

Formula unit

Chemcal formula for an ionic compound (represents the simplest ratio of the ions involved)

Oxidation number

The charge of monoatomic ion, which is one-atom ion, such as Mg₂₊

Metallic bonds

The attraction of a metallic cation for delocalized electrons, which are free to moce electrons

Properties of metals

Malleability, ductility, and durability

Hardness and strength

High melting and boiling points

High thermal and electrical conductivity

Metal alloys

A mixture of elements that has metallic properties

Covalent bond

A chemical bond that results from sharing valence electrons

Lewis structure

Represent the arrangement of electrons in a molecule

Electron-dot diagrams

Used to show valence electrons of atoms

AA line or pair of vertical dots between the symbols of elements

Represents a single covalent bond in a Lewis structure

Single bond

When one electron gets shared

Double bonds

When two electrons get shared

Triple bond

When three electrons get shared

Sigma bonds

Strong bond and can form when an s orbital with another s orbital or porbital or two p orbitals overlap end-to-end

Pi bond

Represented by the symbol (π), forms when parallel orbitals overlap and share electrons

Bond length

The distance between two bonded nuclei at the position of maximum attraction

The shorter the bond length

The stronger the bond

As the number of shared electron pairs increases

The bond length decreases

Bond-dissociation energy

The amount of energy required to break a specific covalent bond and it is always a positive value

Endothermic reaction

A chemical or physical process that absorbs heat from its surroundings, resulting in a decrease in the surrounding temperature and a net increase in the system's enthalpy

Exothermic reaction

A chemical process that releases energy into its surroundings, usually in the form of heat or light, causing the temperature of the environment to rise

Nonpolar covalent bond (or pure covalent)

Occurs when two atoms share electrons equally, resulting in no separation of charge

Polar covalent bond

A type of chemical bond where electrons are shared unequally between two non-metal atoms due to differences in electronegativity

Partial charge

A non-integer electric charge value (less than a full 电子 charge) that occurs on atoms within a molecule due to unequal electron sharing in polar covalent bonds

Van Der Waals forces (London forces or dispersion forces)

Weak, short-range electrostatic attractions between atoms or molecules, acting as the primary force in non-polar substances

Dipole-dipole forces

Attractive electrostatic forces between the positive end of one polar molecule and the negative end of another