IB Chemistry Topic 3 & 13 Definitions

This page contains our IB Chemistry definitions for topic 3 & 13. By learning each one of these definitions, you will fully cover the content for IB Chemistry 'Classification of Matter'.
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anion

Non-metals that gain valence electrons to gain a negative charge

atomic radius

Distance from nucleus to valence electron

cation

Positive ions. Commonly metals that lose valence electrons to gain a positive charge.

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chiral carbon

A carbon bonded to four different groups

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cis-isomerism

Attached groups are the same on the same side of the bond plane

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cis-trans isomerism

Isomerism that only occurs with bond rotation restriction and communicates symmetry around the bond plane based on group identity

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complementary colours

two colours opposite one another on a colour wheel 

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complex ion

Complex composed of a central d-block metal ion coordinate bonded to electron-rich ligands

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configurational isomers

Molecules with different arrangements that require bond breaking and reforming to align

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conformational isomers

Molecules with different spatial arrangements that can be aligned by bond rotation

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coordination number

Number of lone pairs bonded to the metal ion

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diastereomer

Optical isomers that are not mirror images of each other

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E-isomerism

The groups with the highest atomic numbers are on opposite sides of the bond plane

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E/Z isomerism

Isomerism that only occurs with bond rotation restriction and communicates symmetry around the bond plane based on atomic number

electron affinity

Energy change during electron addition to an isolated mole of gaseous atoms

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electron repulsion

electrons try to move as far away from each other due to the repelling negative charges 

electronegativity

Relative measure of the attraction an atom has for a shared pair of electrons when covalently bonded to another atom

electrostatic attraction

The attraction of opposite charges between the positive nucleus and negative electrons

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enantiomers

Optical isomers that are mirror images of each other

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fingerprint region

A unique pattern of absorption in the wavenumber region of 1400-400 cm-1

first ionization energy

The energy required to remove one electron from amole of atoms in a gaseous atoms, expressed in kJ/mol

group

one column of the periodic table 

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H NMR

A method that provides information about the environment of hydrogen atoms

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hydrogen environment

The atom that the hydrogen is attached to and atoms bonded to that atom

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index of hydrogen deficiency (IHD)

A measure of saturation of an organic molecule

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infrared spectroscopy

A method that shines infrared light on molecules and measure absorption

ionic radius

Distance from nucleus to valence electron of cation or anion

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ligand

Neutral molecule or anion with a non-bonding pair of electrons (commonly water)

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mass spectrometry

A method that vaporizes and ionizes a sample molecule, and then deflects its into different fragments with magnetic field

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monodentate ligand

One non-bonding electron pair

nuclear charge

The amount of positive charage in the nucleus, proportional to the number of protons

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optical isomerism

Isomerism where two molecules have the same molecular and structural formuals but are not super-imposable

organic compound

A compound containing carbon

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oxidation state

Akin to ionic charge, it represent the number of electrons gained or lost in order to form a covalent bond with another atom

period

one row of the periodic table 

Periodic table

The periodic table is table of all known elements organized in order of increasing atomic number 

periodicity

The repeating pattern of physical and chemical properties shown by different periods

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polarimeter

A device that detects the optical activity of enantiomers

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polydentate ligand

More than one non-bonding electron pair

primary carbon

A carbon bonded to one other carbon

primary nitrogen (amine)

A nitrogen bonded to one carbon

quaternary carbon

A carbon bonded to four other carbons

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racemic mixture

A mixture with equal amounts of enantiomers, which is optically inactive

secondary carbon

A carbon bonded to two other carbons

secondary nitrogen (amine)

A nitrogen bonded to two carbons

shielding effect

The effect of inner electrons taking nuclear charge away from the valence electrons

skeletal formula

Simplified stuctural formulas that only show lines and assume a carbon at each junction is fully saturated with hydrogens

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Spin-spin coupling

Produces the splitting pattern on H-NMR due to the influence of Hydrogen nuclei on other neighbouring Hydrogen nuclei

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stereoisomers

Molecules with the same structural formula but different spatial arrangements

structural isomer

A molecule with the same molecular formula but a different structural formula than another molecule

tertiary carbon

A carbon bonded to three other carbons

tertiary nitrogen (amine)

A nitrogen bonded to three carbons

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trans-isomerism

Attached groups are the same on opposite sides of the bond plane

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transition metal

Elements that form ions with an incomplete d-orbital in one of more of its oxidation states

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valence shell

Outermost energy level of an atom 

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visible light

the part of the electromagnetic spectrum the human eye can see. contains wavelengths from 400nm to 700nm

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X-ray crystallography

A method that shines X-rays on bonds and uses a sensor to detect the diffraction of the X-rays to measure bond length

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Z-isomerism

The groups with the highest atomic numbers are on the same side of the bond plane

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