Chapter 5 Electrons and Bonding Flashcards
What are electron shells?
Regarded as energy levels
Energy increases as shell number increases
She’ll number/ energy number is called the principle quantum number n
What is an orbital?
Shells are made of atomic orbitals which is a region around the nucleus which can hold two electrons with opposite spins
What is an s-orbital?
The electron cloud with a spherical shape
Each shell from n=1 contains 1 s-orbital
What is a p-orbital?
The electron cloud in the shape of a dumb-bell
There are three separate p-orbitals at right angles to each other within a p sub shell
Every she’ll from n=2 contains three p orbitals
What are d and f-orbitals?
These have more complex shapes
Each shell from n=3 has 5 d-orbitals
Each shell from n=4 has 7 f-orbitals
What’s a subshell?
Within a shell, orbitals of the same type are grouped together as sub shells
For example there are three p-orbitals within the second energy shell, these are group as the 2p subshell
What are the rules for filling electrons into shells?
Within each shell, the new type of subshell added has a higher energy
E.g. in the second subshell the 2p subshell is the new type and has higher energy than the 2s subshell
In n=2 2s, 2p
In n=3 3s, 3p, 3d etc.
The highest energy subshell in the third shell overlaps with the lowest energy subshell in the fourth shell e.g. 3d is higher than 4s therefore the 4s fills with electrons first so the order is 3p, 4s, 3d
How are electron spins and shell fillings represented in the ‘Electrons in Box’ model?
In each box (representing orbitals) there is only two arrows (representing electrons)
Each arrow faces opposite directions to show the different spins
When filling a multi-orbital subshell an electron will prefer to have its own orbital rather than share but eventually when the subshell is nearly full the will have to ‘double up’
What is the electronic configuration of krypton?
The way they fill:
1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^10, 4p^6
The way it’s written:
1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^10, 4s^2, 4p^6
The configuration groups energy levels together so it’s written 3p,3d,4s instead
What is noble gas configuration?
This is a shorthand technique to electron configuration. This is done by writing the electron configuration of the previous noble gas plus extra electrons
E.g Potassium, K:
Regular: 1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^1
Noble Gas: [Ar] 4s^1
What are the electron blocks of the periodic table?
The periodic table can be divided into blocks corresponding to their highest energy subshell
S-block = highest energy subshell is a s which is the left two groups of the periodic table
P-block = highest energy subshell is a p which is the right six groups of the periodic table
D-block = highest energy subshell is a d which is the centre ten groups of the periodic table
How do the elements of the d-block form ions?
The 4s subshell is at a lower energy than the 3d subshell so it’s filled first. However they are very close together so once filled the 3d energy level falls below that of the 4s the consequence of that is:
The 4s fills before the 3d
The 4s empties before the 3d when forming ions.
What is an ionic bond?
Electrostatic attraction between positive and negative ions
This force of attraction is in all directions and not localised
What model is used to display ionic bonds?
Dot and across diagrams with square brackets to show the ions formed
Summarise the properties of ionic compounds.
High mp/bp
Tend to dissolve in polar solvents like water
Conduct electricity as liquids (molten or dissolved)
