Chapter 5 Flashcards
What are the shells regarded as?
Energy levels, which are called the principal quantum number, n.
How can electrons move between energy levels?
They move by absorbing or emitting energy equal to the difference in energy between two energy levels.
What is an atomic orbital?
A region around the nucleus which can hold up to 2 electrons with opposite spins. It is also a region of space where there is a high proportion of finding an electron with a certain quanta of energy.
What are s- orbitals?
The electron cloud, is a sphere shape, with each shell from n=1 upwards containing 1 s-orbital. The greater the shell numbers the greater the radius of its s-orbital.
What are p- orbitals?
They have an electron cloud shaped like a dumbbell, which have 3 separate orbitals all at right angles of one another. Each shell from n=2 has 3 p-orbitals. The greater the shell number the further the p orbital is from the nucleus.
What are d-orbitals and f-orbitals?
Each shell from n= 3 contains 5 d- orbitals
Each shell from n=4 contains 7 f-orbitals
How many electrons are there in each shell?
n=1 –> 2
n=2 –> 8
n=3 –> 18
n=4 –> 32
What are sub shells?
Within a shell, orbitals of the same type are grouped into sub shells. Each shell gains a new type of orbital, the number of orbitals increase with the each new orbital type. Two electrons can fit in each orbital, so the number of electrons in a sub shell also increases.
How do the orbitals fill?
They fill in order of increasing energy, the new type of shell added to each shell has a higher energy level.
Tell me the order of how the orbitals fill?
n=2 2s, 2p
n=3 3s,3p,3d
n=4 4s,4p,4d,4f
Where is there an overlap with orbitals?
The highest energy level on n=3 overlaps with the lowest level of n=4. The 3d has a higher energy level than the 4s, so the 4s fills before the 3d. So the order goes 3p,4s,3d
Describe electron pairs with opposite spins?
Each orbital can hold 2 electrons with opposite spins. As electrons are negatively charged they repel each other. They spin, either up or down. An electron can be shown as an arrow indicating its spin. Two electrons in a orbital must have opposite spins to covert the repulsion between the negative charges.
How does the electrons pair?
One electron has to occupy each orbital before pairing can start, this prevents any repulsion between the paired electrons until there is no further orbital available at the same energy level.
What happens when ions form?
The highest energy levels lose or gain electrons
What happens with the 4s sub shell when electrons are gained and lost?
It fills before 3d and empties before 3d.
What is ionic bonding?
It is the electrostatic attraction between positive and negative ions. It holds cations and anions in ionic compounds.
How are ionic compounds indicated?
Using a dot and cross diagram., with only the outer electrons being represented, with the electrons being transferred from the metal to the non metal. The diagram should be separate with brackets around them, with their ionic charge shown in the upper right hand corner.
Describe the structure of ionic compounds?
Each ion attracts oppositely charged ions very strongly, in all directions. This results in a giant ionic lattice which contains billions of ions, this structure occurs at solid state. Ions are packed closely together in a regular lattice arrangement.
Do ionic compounds have high or low melting points?
Almost all are solid at room temperature, as there is insufficient amount of energy to overcome the electrostatic forces between the opposite charged ions in a giant ionic lattice. High temperatures are required to overcome the electrostatic attraction between the ions. Therefore most ionic compounds have a high melting and boiling point.
Describe the solubility of ionic compounds?
Many ionic compounds dissolve in polar solvents. Polar water molecules break down the lattice and surrounds each ion in the solution. If a compound has a large ionic charge the attraction maybe too strong for water to break down the lattice, so the compound won’t be very soluble.
What does solubility depend on?
The relative strengths of attraction within the lattice and attractions between the ions and water. Solubility decreases as the ionic charges increase
What are the two processes which solubility of ionic compounds require?
The ionic lattice must be broken down
Water molecules must attract the surrounding ions
What is the electrical conductivity of ionic compounds?
In a solid state, the ionic compound can’t conduct electricity unless it is dissolved or melted. In the solid state, the ions are fixed into position in the giant lattice structure, where there are no mobile charge carriers. However in a aqueous or melted state, the solid ionic lattice breaks down and the ions are free to move as mobile charge carriers, so can now conduct electricity
What is covalent bonding?
It is the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.
