atomic structure Flashcards
(36 cards)
what is the mass of an electron relative to the mass of a proton?
1/1836
why does the electron have a greater extent of deflection?
this is because the electron has a greater charge-to-mass ratio
how to calculate the angle of deflection
k (charge/mass)
define mass number
it is the total number of protons and neutrons in the nucleus of an atom
define atomic number
it is the number of protons in the nucleus of an atom
define isotopes
they are atoms of the same element with the same number of protons and electrons but with a different number of neutrons.
what are isoelectronic species?
it is a group of atoms and ions having the same number of electrons
what is an alpha particle?
it is basically a helium atom
what is a beta particle?
it is basically releasing an “electron”, causing the atomic number to increase by 1.
what happens as the principal quantum number (n) increases?
the orbital becomes larger, the electron density is further away from the nucleus, the electrons have higher energy, and a weaker electrostatic attraction between the nucleus and the electron.
what is an atomic orbital?
it is a region of space in which there is a 95% probability of locating the electron residing in it.
what is a ‘p’ orbital?
it is dumb-bell in shape and directional along the x, y, z axes. for the same n, they are degenerate. as n increases, orbital size increases and the p orbital becomes more diffuse.
what is an ‘s’ orbital?
it is spherical in shape and non-directional. as n increases, the orbital size increases and the ‘s’ orbital becomes more diffuse.
what is a ‘d’ orbital?
it has 5 orbitals which are degenerate and 4 of them look like a clover leaf.
state electronic configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p…
what is hund’s rule?
electrons of parallel spins occupy singly in orbitals of a subshell in order to minimise inter-electronic repulsion.
how does nuclear charge affect the strength of electrostatic attraction between the nucleus and electrons?
as the number of protons increases, the nuclear charge increases which means that electrostatic attraction increases.
how does the shielding effect affect the strength of electrostatic attraction between the nucleus and electrons?
when the number of inner shell electrons increases, shielding effect experienced by the valence electrons increases which results in electrostatic attraction to decrease.
how does the number of principal quantum shells affect the strength of electrostatic attraction between the nucleus and electrons?
the distance between the nucleus and the valence electrons increases which means that electrostatic attraction decreases.
how to calculate effective nuclear charge?
subtract shielding effect from nuclear charge
define first ionisation energy.
the first IE or an element is defined as the energy absorbed to remove one mole of electrons from one mole of gaseous atoms to form one mole of singly charged positive gaseous ions.
what is atomic radius?
it is half the shortest inter-nuclear distance found in the structure of the element.
define electronegativity
it is a measure of the ability of an atom in a molecule to attract a shared pair of electrons in a covalent bond.
why does electrostatic attraction increase across a period?
across a period, there is an increasing nuclear charge due to an increase in the number of protons. there is an approx. constant shielding effect as additional electrons are added to the same valence shell. effective nuclear charge hence increases and the valence electrons experience stronger nuclear attraction.
