atomic structure Flashcards
Atoms
An atom is the smallest indivisible particle of an element that can take part in a chemical reaction.
Protons (charge, relative mass)
Charge: 1+
Relative mass: 1
Neutron (charge, relative mass)
Charge: 0
Relative mass: 1
Electron (charge, relative mass)
Charge: 1-
Relative mass: 1/1840
Behavior of particles in an electric field
Protons: deflected towards the negative plate
Electrons: deflected towards the positive plate
Neutrons: not deflected at all
Extent of deflection of protons and electrons
The extent of deflection of electrons towards the positive plate in the electric field will be greater than protons as an electron has a much smaller mass than a proton.
Extent of deflection equation
Charge / mass
Isotopes (definition)
Isotopes are atoms of the same element with different number of neutrons
Isotopes (properties)
Isotopes of the same element have the same chemical properties, because they have the same number of electrons. However, they have slightly different physical properties, due to the different relative masses of isotopes.
Atomic orbitals
An orbital is a region of space around the nucleus with the highest probability of locating the electrons
s orbitals
All s orbitals are spherical in shape, they only differ in size
p orbitals
There are 3 types of p orbitals (px,py,pz) with different orientations in space. Each p orbital has a dumb-bell shape
Four types of orbitals
s, p, d, f
Maximum number of electrons that can occupy each shell
2n 2
Maximum number of electrons each orbital can hold
2
Subshell s
1 orbital, maximum of 2 electrons
Subshell p
3 orbitals, maximum 6 electrons
Subshell d
5 orbitals, maximum 10 electrons
Subshell f
7 orbitals, maximum 14 electrons
Electron shell 1
1 subshell (1s), maximum 2 electrons
Electron shell 2
2 subshell (2s, 2p), maximum 8 electrons
Electron shell 3
3 subshell (3s, 3p, 3d), maximum 18 electrons
Electron shell 4
4 subshell (4s, 4p, 4d, 4f), maximum 32 electrons
4s vs 3d subshells
The orbitals are always filled in the order of increasing energy. Electrons always go into an empty orbital with the lowest energy first.
4s has a lower energy level than 3d. Thus, when adding electrons, the 4s orbital is filled up before the 3d orbital.
Ions (definition)
An ion is formed when an atom loses or gains electron(s), such that it acquires an electrical charge. Atoms lost or gain electrons to obtain the duplet or octet configuration in order to achieve greater stability
Formation of ions (anion)
When atoms gain elections, negative ions are formed (anions).
Electrons are first added into available orbitals with the lowest energy.
Formation of ions (cations)
When atoms lose electrons, positive ions are formed (cations).
Electrons are first removed from orbitals with the highest energy. When the 3d orbital is filled, the energy level of the 4s orbital will increase above that of the 3d orbital. Thus, during the formation of cations, the electrons will be removed from the 4s orbital before the 3d orbital.
Isoelectric species
Any atom or ions with same number of electrons are said to be isoelectronic.