Topic 1 - Atomic Structure Flashcards
Name the Particles
Atoms
Molecules
Ions
Electrons
Relate speed of particles to temperature
Speed of particle movement is directly proportional to temperature
Define - Atom
The smallest part of an element that can take part/participate in a chemical reaction because it retains the chemical properties of the element
What is the shape of an atom?
• spherical - not rigid but clouded because electrons are free to move
•
Define principle quantum number
Energy levels around a nucleus
All of them are quantised
How does energy change as you move away from the nucleus?
The shell nearest to the nucleus has the least energy and the energy level increases as you move away from the nucleus
What is the formula predicting the number of electrons a principal quantum number can hold?
2n ^2
Describe the nucleus
Positively charged dense central region of an atom which is responsible for the particulate nature of the atom
What are the different types of subshells?
s
p
d
f
What is the shape of the s-subshell?
Spherical
How many orbitals does the s-subshell have?
One
Define - Ionisation Energy
Energy required to remove one mole of electrons from one mole of gaseous atoms or cations
Define - Ionisation
The process of removing an electron from a gaseous atom or from a gaseous cation
Why is Ionisation energy endothermic?
Energy is always needed to overcome the electrostatic force of attraction between the nucleus and the electron being removed
Define First Ionisation energy
The amount of energy required to remove 1 mol of electrons from 1 mol of gaseous atoms to form 1 mol of a positively charged ion with a +1 charge
Define Second Ionisation energy
The amount of energy required to remove 1 mol of electrons from a gaseous cation with charge +1 to form a positively charged cation with +2 charge
What is the first factor that determines ionisation energy?
Radius - the larger the atom the lower the ionisation energy, as the valency electrons (those that are lost) are farther away from nucleus and therefore are more loosely held
What is the trend in Ionisation energy down a group?
It decreases as you go down because the radius of the atoms increases
What is the second factor determining ionisation energy?
Nuclear Charge
The more protons that are held by the nucleus, the greater the nuclear charge, the more strongly the electrons are held and therefore the higher the ionisation energy
What is the trend in ionisation energy across a period?
I.E increases as you go across the period as the nuclear charge is also increasing
LEFT TO RIGHT
What is the third factor determining Ionisation Energy?
Shielding/screening effect
This is when the electrons closer to the nucleus shield the outer electrons from the nucleus, (repulsion) making them easier to lose as they are farther from the nucleus and held more loosely
Evidence of the existence of shells
Successive I.E of one element
The big jumps if they were plotted on a graph show how many shells there are
Evidence for the existence of subshells
The first ionisation energy of successive elements
Define - Effective Nuclear Charge
The amount of nuclear charge that manages to reach the outer shell and stay there
How many orbitals does the p sub-shell have?
Three
Nucleus at the node of the dumbell
How many orbitals does the d subshell have?
Five
10 electrons held
Define
Degenerate orbitals
orbitals that are at the same energy level
electrons can slide between the orbitals
Define
Half filled stability
When a subshell is half filled it means it is experiencing minimal repulsion and is therefore more stable
Define
Full filled stability
When a subshell is fully filled it has extra electronic stability
Why does Boron have a lower first IE than expected?
The first electron is removed from a P orbital which is farther away from the nucleus and more shielded (less strongly held)
Why does Beryllium
have a higher first IE than expected?
First electron to be removed from an s subshell with a pair and more energy is needed to over come the strong forces of attraction between the electrons with opposite spins
Why does Phosphorus have a higher first IE than expected?
First electron is removed from a half filled sub-shell, where orbitals occupy the space singly, experience minimal repulsion (half filled stability)
Why does sulphur have a lower first IE than expected?
First electron is removed from an orbital that has a pair where the electrons experience spin-spin repulsion
Why does sulphur have a lower first IE than expected?
First electron is removed from an orbital that has a pair where the electrons experience spin-spin repulsion
Define
Spin pair repulsion
When two electrons in an orbital have the same spin they repel each other
