(U1) Atomic Structure Flashcards
What is atomic number?
The number of protons in the nucleus of an atom
What is mass number?
The total number of protons and neutrons in the nucleus of an atom.
What is Relative Atomic Mass (RAM) (3)
- The weighted mean mass
- of an atom of an element
- relative to 1/12 of the mass of an atom of carbon-12
What is Relative Isotopic Mass (RIM) (3)
- The weighted mean mass
- of an atom of an isotope of an element
- relative to 1/12 of the mass of an atom of carbon-12
What are isotopes? (2)
- Atoms which contain the same number of protons
- but a different number of neutrons
What is Relative Molecular Mass (RMM) (3)
- The weighted mean mass
- of a molecule
- relative to 1/12 the mass of an atom of carbon-12
What is Relative Formula Mass (RFM) (2)
- The weighted mean mass of a species
- relative to 1/12 the mass of an atom of carbon-12
What is a molecular ion?
2 or more atoms covalently bonded with an overall charge
What is First Ionisation Energy? (2)
- The energy required to convert one mole of gaseous atoms
- into gaseous ions with a single positive charge
What is Second Ionisation Energy? (2)
- The energy required to convert one mole of gaseous ions with a single positive charge
- into gaseous ions with a double positive charge
What is Third Ionisation Energy? (2)
- The energy required to convert one mole of gaseous ions with a double positive charge
- into gaseous ions with a triple positive charge
Using a mass spectrometer, how do you calculate relative atomic mass?
(percentage abundance) x (mass charge ratio) / 100
What is an orbital? (2)
- a region within an atom that can hold up to 2 electrons
- within opposite spins
What shape is an S-type orbital?
Spherical
What shape is a P-type orbital?
Dumbbell
State Hund’s Rule (2)
- where electrons have choice between orbitals of equal energy
- they will fill the orbitals singly as far as possible
State the order of filling for energy levels (up to 9th)
- 1s
- 2s
- 2p, 3s
- 3p, 4s
- 3d, 4p
Why is 4s filled before 3d?
4s is closer to the nucleus than 3d
In s, p, d, f notation, what do the letters represent?
How many electrons can s, p and d hold?
- Sub shells
- s holds 2, p holds 6, d holds 10
What atom does the electronic configuration 1s2 represent?
What does this mean?
- an atom of helium
- the 1st ‘s’ sub shell is filled with 2 electrons
State the general equation for 1st ionization energy
X(g) —> X+(g) + e-
State the general equation for 2nd ionization energy
X+(g) —> X2+(g) + e-
State the general equation for 3rd ionization energy
X2+(g) —> X3+(g) + e-
Why does ionization energy usually increase across a period? (3)
- increased nuclear charge
- Decrease in atomic radius
- same number of shielding electrons
What is the electronic configuration of Cr (using noble gas notation)
Why is it irregular?
- [Ar] 3d5 4s1
- the 4s subshell loses an electron to the 3d subshell to form a half filled subshell (more stable)
What is the electronic configuration of Cu (using noble gas notation)
Why is it irregular?
- [Ar] 3d10 4s1
- the 4s subshell loses an electron to the 3d subshell to form a filled subshell (stable)
What 2 elements are exceptions to the rule for the filling of orbitals?
- Cu
- Cr
Why does ionization energy not increase regularly across a period?
- some have higher than expected energies due to filled and half filled subshells
- transition metals increase marginally due to 3d subshell shielding 4s effectively
What happens to 1st ionization energy down a group?
Why?
- decreases
- increase in atomic radius and more energy levels —> more shielding —> attraction weakens
What are valence electrons?
Outer electrons
How many orbitals are in a:
- p-subshell
- s-subshell
- d-subshell
- p = 3 orbitals
- s = 1 orbital
- d = 5 orbitals
State and explain the general trend in the first ionization energy across the second period.
Identify and explain any exceptions
(7)
- 1st ionization energy increases left to right
- due to:
1. increase in nuclear charge
2. Decrease in distance between nucleus and outer electrons
3. Same number of shielding electrons - exceptions: Be and N
- Be —> full outer subshell —> stability —> more energy needed
- N —> half full outer subshell —> stability —> more energy needed
When forming cations, which orbital are electrons removed from first in Cr?
Why?
- The 4s subshell
- 4s is further away from the nucleus than 3d
What are the relative masses and charges of:
- Protons
- Neutrons
- Electrons
- Protons
- mass = 1
- charge = +1
- Neutrons
- mass = 1
- charge = 0
- Electrons
- mass = 1/1840
- charge = -1
How do you calculate relative atomic mass from mass spectra?
(equation)
RAM = percentage abundance (%) x mass charge ratio (Z) / 100
On the periodic table, where is the:
- s-block
- p-block
- d-block
- f-block
Why are they called this?
- S-block = groups 1 and 2
- P-block = groups 5 to 8
- D-block = transition metals
- F-block = lanthanum series
Name comes from their outermost subshell
In box notation, how do you represent electrons?
⥮ one arrow up, one arrow down - representing 2 electrons in opposite spins (within an orbital) ⥮
What does a large difference (compared to 3rd ionisation energy etc.) in 2nd ionisation energy confirm?
Why? (2)
The presence of energy levels:
- first electron lost easily as it is in a shell furthest from the nucleus (greater atomic radius) and separated by greater shielding, therefore electrostatic attraction is weakest
- 2nd electron closer to nucleus and requires more energy to overcome stronger electrostatic attraction
What is the affect of ionisation on effective nuclear charge?
Increased ionisation = greater effective nuclear charge
(greater ratio of protons to electrons)
