Glossary For First Test Flashcards
Atom
Smallest constituent unit of ordinary matter that has the properties of a chemical element
Made up of a nucleus and a cloud of electrons
Electron
Subatomic particle with a negative elementary electric charge
Nucleus
Small, dense region consisting of protons and neutrons at the centre of an atom
Ion
Atom/molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge
Cation
A positive ion, there are fewer electrons than protons
Anion
A negative ion, there are more electrons than protons
Molecule
Electrically neutral group of two or more atoms held together by chemical bonds
Electron configuration
Distribution of electrons of on atom/molecule amongst its atomic/molecular orbitals
Electron shell / principal energy level
An orbit followed by electrons around an atom’s nucleus
Electron sub-shell
Each shell is composed of one or more subshells of different symmetry which are themselves composed of separate atomic orbitals
Atomic/molecular orbitals
Mathematical function that describes the wave like behavior of either one election or a pair of electrons in an atom/molecule
Relative atomic Mass
The average mass of atoms of a particular element, taking into account all of its isotopes in their natural abundance
Electronegativity
Chemical property that describes the tendency of an atom or a functional group to attract or pull electrons towards itself
Metallic bond
Occurs as a result of electromagnetism and describes the electrostatic attractive force that occurs between conduction electrons (in the form of on electron cloud of delocalised electrons) and positively charged metal ions
Covalent bond
Chemical bond that involves sharing electron pairs between atoms
The covalent bonding orbital is a linear combination of atomic orbitals and is lower in energy than those
Sigma bond
Strongest type of covalent chemical bond that is formed by head-on overlapping between atomic orbitals
Pi bond
Covalent chemical bond where two lobes of one involved atomic orbital overlap two lobes of the other involved atomic orbital. Each of these atomic orbitals is zero at a shared nodal plane, passing though the two bonded nuclei. The same plane is also a nodal plane for the molecular orbital of the pi bond
Bond polarity
Separation of electric charge leading to a molecule or its chemical groups having on electric dipole or multiple moment
Molecular polarity is dependent on the difference in electronegativity between atoms in a compound and the asymmetry of the compound’s structure
Delocalised electrons
Electrons in a molecule/ion/solid metal that are not located on a single atom or in a particular bond but are spread out over two or more atoms
Stoichiometry
Whole number ratio of moles in which two substances react together to form products
