U3 revision key terms

Question 1

Ionic bond

Answer 1

Electrostatic attraction between oppositely charged ions that holds the ions in close proximity.

The ionic bond forms between metal +non-metal

Question 2

Electrostatic attraction

Answer 2

A non-contact attractive force that occurs between particles of opposite charge.

静电吸引力

Question 3

Binary Ionic compound

Answer 3

Is Composed of ions of two different elements

Question 4

Lattice

Answer 4

A three-dimensional regular repeating arrangement of ions, atoms or molecules in a crystalline solid.

Question 5

Metallic Bond

Answer 5

The electrostatic attraction between a lattice of positive metal ions and a sea of delocalized electrons.

The metallic bond forms between metal + metal

Question 6

Delocalized electrons 游离电子

Answer 6

An electron that is not associated with one specific atom and is free to move within the molecular structure.

Question 7

Alloys 合金

Answer 7

Homogeneous mixtures of a metal and other metals or non-metals.

Question 8

Covalent bond

Answer 8

The electrostatic force of attraction between two positive nuclei and a shared pair of electrons.

The covalent bond forms between non-metals + non-metals

Question 9

Polar covalent bond
极性共价键

Answer 9

A bond which has a partially positive end and a partially negative end due to asymmetrical electron distribution caused by the difference in electronegativity of the two bonded species.

A polar covalent bond has an asymmetric bonding orbital electron density function with non-equal sharing of the bonding electrons

Question 10

non-polar covalent bond
非极性共价键

Answer 10

A covalent bond formed between two atoms with equal electronegativity values which results in equal sharing of the electrons in their bond.

A nonpolar covalent bond has a symmetric bonding orbital electron density function with equal sharing of the bonding electron.

Question 11

Electronegativity (χ)

Answer 11

the ability of an atom in a molecule or an ion to attract electrons to itself

Question 12

Dipole (movement)

Answer 12

The two separated opposite electric charges, δ+ and δ-, existing in a polar bond.

Question 13

Covalent Network Solids

Answer 13

Covalent network solids are composed of atoms covalently bonded together into a three-dimensional network or layers of two-dimensional networks. Due to the strength of the covalent bonds, covalent network solids have high melting points.

(e.g 3d: Diamond , Silica. (hard and rigid) 2d: graphite (soft due to the easy slide past each other ))

Question 14

Coordination Bond

Answer 14

(also called a dative covalent bond) is a covalent bond (a shared pair of electrons) in which both electrons come from the same atom

Question 15

Octet rule

Answer 15

The tendency of an atom to achieve stability by ensuring its valence shell is full, either by gaining, losing or sharing electrons.

Question 16

VSEPR theory

Answer 16

Valence Shell Electron Pair Repulsion theory: A theory used to explain and predict molecular geometry, based on numbers of electron domains (bonded and non-bonded electron pairs).

Question 17

London Dispersion Forces

Answer 17

The temporary instantaneous dipole formed due to the rapid and random motion of electrons.

Question 18

Dipole-Dipole Forces

Answer 18

An intermolecular force between two polar molecules that have permanent dipoles. Attractive forces exist between the positive end of one polar molecule and the negative end of another polar molecule.

Question 19

Hydrogen bonding

Answer 19

The intermolecular attraction between two molecules which both contain a hydrogen bonded to a highly electronegative element such as oxygen (O), fluorine (F), or nitrogen (N).

Question 20

Chromatography

Answer 20

Chromatography is an important biophysical technique that enables the separation, identification, and purification of the components of a mixture for qualitative and quantitative analysis.

Question 21

Resonance Structure/hybrid

Answer 21

resonance hybrid:
An intermediate form of a molecule which exists when more than one valid Lewis formula can be drawn.

Resonance is a way of describing delocalized electrons within certain molecules or polyatomic ions where the bonding cannot be expressed by a single Lewis formula.
A molecule or ion with such delocalized electrons is represented by several contributing structures (also called resonance structures or canonical forms).

Question 22

Expanded octet

Answer 22

The ability of a central atom from period 3 or below to achieve stability with more than 8 electrons in its outer shell. For example, Xe, P, or S.

Question 23

Molecular Geometry

Answer 23

The three-dimensional arrangement of the atoms in a molecule, determined using VSEPR theory.

Question 24

Formal charge

Answer 24

The theoretical charge of an entire molecule based on the electron distribution of the atoms within the molecule.

Question 25

Sigma and pi bonds

Answer 25

Sigma bond: A bond formed when atomic orbitals overlap head-on and the electron density is concentrated along the bond axis. Pi bond: A bond formed when one atomic orbital overlaps sideways with another atomic orbital, with electron density concentrated on opposite sides of the bond axis

Question 26

Hybridization (sp3, sp2, sp)

Answer 26

The process by which atomic orbitals within an atom mix to produce hybrid orbitals of intermediate energy. sp3: A form of hybridization that involves 1 s-orbital and 3 p-orbitals. sp2: A form of hybridization that involves 1 s-orbital and 2 p-orbitals. sp: A form of hybridization that involves 1 s-orbital and 1 p-orbital.

Question 27

electron domain (Geometry)

Answer 27

Electron domain: The region in which bonding and non-bonding pairs of electrons are most likely to be found. Non-bonding pairs, single bonds, double bonds and triple bonds each count as one electron domain. Electron domain geometry: The shape of the arrangement of electron domains surrounding a central atom in a molecule or ion