Unit 1 Definitions

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  • Created on: 23-05-16 15:31
Relative Atomic Mass (Ar)
The ratio of the average mass of an atom to 1/12th of the mass of one atom of carbon-12
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Relative Molecular Mass (Mr) / Relative formula mass
The ratio of the average mass of a molecule (or formula unit) to 1/12th of the mass of carbon-12
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Atomic number (Z)
The number of protons in the nucleus of an atom
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Mass number (A)
The total number of protons and neutrons in the nucleus of an atom
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Isotopes
An element with the same number of protons and a different number or neutrons. This changes the mass but does not change the chemical properties of an element
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First Ionisation Energy
The enthalpy change when an electron is removed from a gaseous ion to form a uni-positive gaseous ion.
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Second Ionisation Energy
The enthalpy change when an electron is removed from a uni-positive gaseous ion to form a gaseous ion with a 2+ charge
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Mole
The amount of a substance that has the same number of particles as there are atoms in 12g of Carbon-12
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Avogadro’s Constant
The number of particles in one mole of a substance is 6.02 x 1023 (The number of atoms in 12g of Carbon-12)
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Empirical Formula
The simplest whole number ratio of elements that are present in the compound
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Molecular Formula
The actual number of atoms of each element in each molecule of a substance
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Atom Economy
The proportion of the products of a reaction compared to the desired products
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Ionic Bond
The electrostatic attraction between positive and negative ions held in a crystal lattice
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Single Covalent Bond
When 2 electrons are shared in a covalent bond between two non-metals
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Double Covalent Bond
When 4 electrons are shared in a covalent bond between two non-metals
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Dative/Co-ordinate Bond
When one atom donates both the electrons to form the covalent bond
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Metallic Bond
The force of attraction between a lattice of positive ions surrounded by a sea of delocalised electrons.
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Electronegativity
The power of an atom to attract the electron density in a covalent bond towards itself
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Electron Affinity
How easily the electrons are lost and gained
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Electron Pair Repulsion Theory
A theory which explains the shapes of simple molecules by assuming that the pairs of electrons around a central atom repel each other, taking up positions as far away as possible from each other in space
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Van der Waals
A force of attraction caused by instantaneous dipoles and acts between all atoms and molecules
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Permanent Dipole-Dipole
An intermolecular force that results from the attraction between molecules with permanent dipoles
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Hydrogen Bonds
A hydrogen atom, covalently bonded to an electronegative atom, interacts with ………………………another electronegative atom
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Relative Isotopic Mass
The ratio of the mass of one atom of that isotope to 1/12th of the mass of one atom of carbon-12
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Other cards in this set

Card 2

Front

Relative Molecular Mass (Mr) / Relative formula mass

Back

The ratio of the average mass of a molecule (or formula unit) to 1/12th of the mass of carbon-12

Card 3

Front

Atomic number (Z)

Back

Preview of the front of card 3

Card 4

Front

Mass number (A)

Back

Preview of the front of card 4

Card 5

Front

Isotopes

Back

Preview of the front of card 5
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