Chapter 5 - Electrons and bonding Flashcards
(31 cards)
What are shells regarded as?
Shells are regarded as energy levels and the energy increases as the shell number increases.
What is the shell number or energy level number called?
The principle quantum number n.
What is the maximum number of electrons a shell n can hold?
Number of electrons: 2n^2.
What are shells made up of?
Shells are made up of atomic orbitals.
What is an atomic orbital?
An atomic orbital is a region around the nucleus that can hold up to two electrons, with opposite spin. Models visualise an atomic orbital as a region of space where there is a high probability of finding an electron.
What is the maximum number of electrons an orbital can hold?
An orbital can hold two electrons at most.
What are the different types of orbitals?
S-, p-, d- and f- orbitals.
What is the shape of an S orbital and what happens as the shell number increases?
In an s orbital the electron cloud is within the shape of a sphere. As with all orbitals, an s-orbital can hold one or two electrons. Each shell from n=1 contains one s orbital and the greater the shell number n, the greater the radius of its s orbital.
What is the shape of an P orbital and what happens as the shell number increases?
a. In a p orbital, the electron cloud is within the shape of a dumb-bell. As with an s-orbital, one orbital can contain up to two electrons. There are three separate p orbitals at right angles to one another. These orbitals are referred to as Px, Py, and Pz.
b. Each shell from n=2 contains three p orbitals and the greater the shell number n, the further the p orbital is from the nucleus.
What are the properties of d- and f-orbitals?
a. Each shell from n=3 contains five d orbitals.
b. Each shell from n=4 contains seven f-orbitals.
Within a shell what are orbitals of the same type grouped together as?
They are grouped together as sub-shells.
What does each new shell gain in terms of orbitals?
Each new shell gains a new type of orbital.
How does an orbital fill within a shell?
Within each shell, the new type of sub-shell added has a higher energy. For example, in the second shell, the 2p sub-shell is the new type, and is at a higher energy than the 2s sub-shell.
In the third shell what is the highest energy level, and does it overlap with any orbitals in the fourth shell?
The 3d subshell is at a higher energy level than the 4s sub shell. The 4s subshell therefore fills before the 3d subshell. The order of filling is therefore 3p, 4s, 3d.
What property do electrons have and how is this displayed in an orbital?
Electrons have a property called spin – either up or down. The two electrons in an orbital must have opposite spins. The opposite spins help to counteract the repulsion between the negative charges of the two electrons.
Should electron configurations be shown in shell order or the order of filling?
Should be shown in shell order.
Why is the periodic table divided into s, p and d blocks?
a. The periodic table can be divided into blocks corresponding to the highest energy sub-shell.
b. Within the s-block the highest energy electrons are in the s-sub-shell.
c. Within the p-block the highest energy electrons are in the p-sub-shell.
d. Within the d-block the highest energy electrons are in the d-sub-shell.
When forming ions how can you alter the electron configuration?
When forming ions, the highest energy sub-shells lose or gain electrons.
What happens when forming ions of the d-block elements?
The 4s subshell is initially at a lower energy state than the 3d sub-shell, so is filled first. However, once filled the 3d energy level falls below the 4s energy level. Therefore, the 4s electrons are first in and the 4s electrons are first out.
What is ionic bonding?
Ionic bonding is the electrostatic attraction between positive and negative ions. It holds together cations and anions in ionic compounds.
In which directions do ions attract in ionic bonding?
Each ion attracts oppositely charged ions in all directions.
What structure does ionic bonding result in?
Ionic bonding results in a giant ionic lattice structure containing billions and billions of ions, the actual number only determined by the size of the crystal.
In sodium chloride how many ions surround each corresponding ion?
a. Each Na+ ion is surrounded by 6 Cl- ions.
b. Each Cl- ion is surrounded by 6 Na+ ions.
Within ionic compounds what are the similarities in melting and boiling points?
a. Almost all ionic compounds are solids at room temperature. At room temperature there is insufficient energy to overcome the strong electrostatic forces of attraction between the oppositely charged ions in the giant ionic lattice. High temperatures are needed to provide the large quantity of energy needed to overcome the strong electrostatic force of attraction between ions. Therefore, most ionic compounds have high melting and boiling points.
b. The melting points are higher for lattices containing ions with greater ionic charges, as there is a stronger attraction between ions.
