1: Elements and the Periodic Table Flashcards
(46 cards)
What are Nucleons?
Protons + Neutrons
Element definition
A group of atoms with the SAME ATOMIC NO.
Isotope definition
Two atoms with the SAME ATOMIC NO. but DIFFERENT MASS NO.
Nuclide Symbol notation
A: Mass no.
X: Chemical symbol
Z: Atomic no.
Orbital definition
Regions of space with the highest probability of finding electrons within a SPECIFIC ENERGY LEVEL
Features of the Quantum Mechanical Model
- Atoms have major energy levels inside called ‘shells’.
- Maximum amount of electrons for any shell no. is ‘2n2’
- Within shells are subshells organized ‘s, p, d, f’
- Within subshells, electrons move in orbitals
- Subshells contain a different number of orbitals
No. of orbitals in ‘s’ subshell
1
No. of orbitals in ‘p’ subshell
3
No. of orbitals in ‘d’ subshell
5
No. of orbitals in ‘f’ subshell
7
Electrons in the same subshell…
have the same energy
Further the shell is from the nucleus….
the greater the energy of the electrons and the number of subshells within that shell
Greater the amount of subshells…
greater the number of atomic orbitals, greater number of electrons in the shell
electron energy in the subshell increases
s < p < d
Aufbau’s Principle
Electrons enter the orbital of LOWEST ENERGY first
Pauli’s Exclusion Principle
An orbital can only hold 0-2 electrons. If there are two electrons in the orbital, they must be spinning in opposite direcitons
Octet Rule
Atoms are most stable with** 8 electrons in their valence shell**
An atom is most stable when:
Electrons are in the lowest possible orbitals (Ground state)
in lowest energy state
Hund’s Rule
When e- occupy equal energy levels (same subshell), one e- enters each orbital until all orbitals contain 1 e- with parallel spin. Then, a second e- can be added to each orbital with opposite spin
Subshells are stable if they are:
Exactly half filled or completely filled
(Chromium and Copper)
Ground state
All e- in an atom are in the lowest possible energy levels (Aligns with Aufbau’s principle)
Excited State
When given energy, e- move to higher orbitals
What happens to an atom in an excited state?
Electrons no. remains unchanged
Electrons don’t fill according to Aufbau’s principle
Isoelectronic
Two ions with the same electron configuration in the ground state
