Atomic Structure Flashcards
What do atoms consist of?
A central nucleus
What does this central nucleus contain?
Protons and neutrons
What is the nucleus surrounded by?
Electrons in energy levels/shells
State what else you know about the atom
Atoms have no electric charge
They contain the same number of protons as electrons
The nucleus is tiny compared to the size of the whole atom
What is the atomic number?
The number of protons
What is the mass number?
The number of protons + the number of neutrons
Name the relative masses of all the subatomic particles
Proton= 1
Neutron = 1
Electron= 1/1836
State the relative charges of all the subatomic particles
Proton= +1
Neutron= 0
Electron= -1
How do you calculate the number of neutrons?
Mass number - atomic number
What do atoms of the same element have?
The same number of protons
It is the number of protons that determines what type of atom it is
Atoms of different elements have different numbers of protons
What is an isotope?
Atoms with the same number of protons but a different number of neutrons
Atoms of the same element with the same atomic number but a different mass number
How are electrons arranged in atoms and ions?
Electrons are arranged in electron shells/ energy levels- which have sub shells
Each sub level consists of electron orbitals
Each orbital can hold two electrons with opposite spins
What are electron orbitals?
A region of space in which the electron spends most of its time- most likely to be in
What are the different sub levels?
s
p
d
f
How many orbitals can be held in each sub level?
s= 1
p= 3
d= 5
Only need to know these three and not d
How are the electron orbitals filled up?
Electrons enter the lowest energy orbital available
Electrons prefer to occupy orbitals on their own and only pair up when no empty orbitals of the same energy are available
What is the aufbau principle?
When electrons enter the lowest energy orbital available
Electrons fill the lowest orbital of energy first starting with the lowest energy level and working its way up to the highest energy level
Fills the 1s before the 2s
What is hunds rule?
Where electrons prefer to occupy orbitals on their own and only pair up when no empty orbitals of the same energy are available
Electrons prefer to be in orbitals on their own before pairing up as this requires more energy
How do electron orbitals fill up in ions?
The electrons in the highest energy levels are lost first
When losing electrons- electrons are lost from 4s before 4d
What happens when electrons fill 4s and 3d?
4s goes above 3d in energy
These energy levels are very close
What are two exceptions to the expected pattern?
Chromium - Cr
Copper- Cu
What is the electron configuration for chromium?
1s2 2s2 2p6 3s2 3p6 4s1 3d5
NOT
1s2 2s2 2p6 3s2 3p6 4s2 3d4
What is the electron configuration for copper?
1s2 2s2 2p6 3s2 3p6 4s1 3d10
NOT
1s2 2s2 2p6 3s2 3p6 4s2 3d9
This is slightly lower in energy arrangement than Cr as the reduced electron repulsion makes up for the fact one electron is in a slightly higher energy level
What does ionisation energies give evidence for?
How electrons are arranged in atoms