Unit 2 Part 1 - shielding and atomic radius Flashcards
20MAR25
What can metal atoms do to form cations?
Loose electrons
What can non-metal atoms do to form anions?
Gain electrons
What is involved in chemical reactions?
Valence electrons
Why are valence electrons more open to external influences?
Because they are furthest from the electrostatic attraction of the nucleus
What do the outer electrons (valence electrons) of metal atoms experience?
A smaller effective nuclear charge than the outer electrons (valence electrons) of non-metals
When does electron transfer happen?
If they are energetically feasible
Why do atomic numbers on periodic table increase by one in each element?
Because a proton is being added to the nucleus
Why are valence electrons not involved in the charge number?
Because they are shielded from the nucleus and repelled by inner electrons
What does the presence of the inner electrons do?
Reduce the attraction of the nucleus for the outer electrons
What is the nucleus shielded by?
The inner electrons
Why is the full attractive force of the nucleus not felt by the outer electrons?
- Distance from the nucleus
- Electrons are at higher energy levels resulting in less electrostatic force - Shielding
- Inner electrons which have lower energy levels repel outer electrons b/c they have like charges
Pattern of atomic radius?
Increases down a group and decreases across a period
What do electrons occupy?
Atomic orbitals
The attraction between the nucleus and the outer electrons increases as the nuclear charge…?
Increases
- Meaning there is a decrease in atomic radius across the period
Why is atomic radius larger as we descend a column?
Down a column:
1.Electrons are further from the nucleus in higher energy levels
2. As the energy level increases the boundary surface (edge of orbital) is further
3. Increasing the number of shielding electrons inside
Why is there a larger nuclear charge (more protons) from left to right of periodic table?
B/c the atomic number increases across a period
When electrons are in the same energy level in a row, what does it cause?
- Larger attractive force to the nucleus on the electron from increased number of protons
- No increase in separation - No increase in shielding across a row
- Larger nucleus, more electrons, but same shielding
What do atomic orbitals represent?
A 99% chance of locating an electron in that area
What is boundary surface?
The inside which represents a 99% chance of finding all of the electrons in the atom
Why is the atomic radii larger as we descend down a column?
- Number of energy levels increases meaning boundary surface is further
- Number of shielding electrons increases
Who has a stronger nuclear charge on the outer electrons?
Non-metals
Trend of Zeff?
Decreases down a group and increases across a period
What does a higher Zeff mean for electrons?
Stronger pull on electrons
why do metal atoms form positive ions?
B/c they have low ionization
