Topic 2 and 12 - Atomic structure
Atomic emission spectra:
The characteristic line spectrum that occurs as a result of energy being
supplied to individual elements. When energy is supplied to an atom, e- are
excited from their ground state to a higher energy level. The e- dropping from
higher energy levels to lower levels emit energy, which can be observed in a
spectrum. As e- can only exist in fixed energy levels, the energy in the
emissions are characteristic for each type of atom. Lines converge toward high
energy end of spectrum as the energy levels themselves are
convergent.
Atomic number: Number of protons in the nucleus.
Aufbau principle: The principle that states that lowest energy levels are filled first. The starting
order is 1s2s2p3s3p4s3d…
Hund’s rule: Orbitals within the same sub-shell are filled singly first.
Ionization energy, first: Energy required to remove one e-- from an atom in its gaseous state. Increases
across a period (due to increasing nuclear attraction), except for slight drops
(due to the commencement of pairing of e- into orbitals ® greater electron repulsion).
Decreases down a group (due to increased number of energy levels ® increased electron
shielding).
Isotope: An atom that contains the same number of protons but a different number of
neutrons.
Mass number: Total number of nucleons.
Mass spectrometer: A device for determining relative atomic masses and their relative abundances.
Composed of:
**vaporizer
(where the sample is vaporized), **ionizer (where atoms are bombarded with high
energy e- ® e-knocked off the atoms. Only ions
with a +1 charge are formed, in practice), **accelerator (where an electric
field accelerates them), **deflector (where a magnetic field deflects them; the
smaller the mass and the higher the charge, the greater the deflection) and
**detector (which measures both the mass and relative amounts of ions
present.
Orbital: A region of space around the nucleus
of an atom that is occupied by a maximum of two e- at any given time. The types
of orbitals are s (spherical), p (dumbbell-shaped), d and f.
Pauli’s exclusion principle: e- in single orbital must have opposite spin.
Relative abundances: The percentage of natural occurrence of an isotope of an
element.
Relative atomic mass: The weighted mean of all the naturally occurring isotopes of the element relative to
12C. No units.
Valence electrons: The e- in the highest main energy level.
Atomic emission spectra:
The characteristic line spectrum that occurs as a result of energy being
supplied to individual elements. When energy is supplied to an atom, e- are
excited from their ground state to a higher energy level. The e- dropping from
higher energy levels to lower levels emit energy, which can be observed in a
spectrum. As e- can only exist in fixed energy levels, the energy in the
emissions are characteristic for each type of atom. Lines converge toward high
energy end of spectrum as the energy levels themselves are
convergent.
Atomic number: Number of protons in the nucleus.
Aufbau principle: The principle that states that lowest energy levels are filled first. The starting
order is 1s2s2p3s3p4s3d…
Hund’s rule: Orbitals within the same sub-shell are filled singly first.
Ionization energy, first: Energy required to remove one e-- from an atom in its gaseous state. Increases
across a period (due to increasing nuclear attraction), except for slight drops
(due to the commencement of pairing of e- into orbitals ® greater electron repulsion).
Decreases down a group (due to increased number of energy levels ® increased electron
shielding).
Isotope: An atom that contains the same number of protons but a different number of
neutrons.
Mass number: Total number of nucleons.
Mass spectrometer: A device for determining relative atomic masses and their relative abundances.
Composed of:
**vaporizer
(where the sample is vaporized), **ionizer (where atoms are bombarded with high
energy e- ® e-knocked off the atoms. Only ions
with a +1 charge are formed, in practice), **accelerator (where an electric
field accelerates them), **deflector (where a magnetic field deflects them; the
smaller the mass and the higher the charge, the greater the deflection) and
**detector (which measures both the mass and relative amounts of ions
present.
Orbital: A region of space around the nucleus
of an atom that is occupied by a maximum of two e- at any given time. The types
of orbitals are s (spherical), p (dumbbell-shaped), d and f.
Pauli’s exclusion principle: e- in single orbital must have opposite spin.
Relative abundances: The percentage of natural occurrence of an isotope of an
element.
Relative atomic mass: The weighted mean of all the naturally occurring isotopes of the element relative to
12C. No units.
Valence electrons: The e- in the highest main energy level.