Unit Four: The Periodic Table Flashcards
Where are Groups #1-18 on the Periodic Table?
Just label the top of the groups with the numbers 1 through 18.
Where are Periods #1-7 on the PT?T
Rows 1 through 7 on the periodic table.
http://www.green-planet-solar-energy.com/images/PT-blank-2.gif
What are the 8 diatomic atoms?
- Hydrogen
- Oxygen
- Nitrogen
- Chlorine
- Fluorine
- Bromine
- Iodine
- AStatine (radioactive)
Define atomic radius
Distance from center of the nucleus to the outermost enegy shell.
Half the distance between the nucleii of two identical, neutral atoms bonded together.
Define ionization energy.
The amount of energy required to remove a valence electron from an atom in gaseuous state.
Define Electronegativity
Tendency of attracting electrons in a bond.
Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. The Pauling scale is the most commonly used. Fluorine (the most electronegative element) is assigned a value of 4.0, and values range down to caesium and francium which are the leastelectronegative at 0.7.
Electron affinity
The energy change associated when a neutral atom gains an electron
Which element has the highest atomic radius and the lowest ionization energy and the lowest electro negativity?
Why?
Francium
Francium has the smallest Zeff; highest atomic radius and lowest IE
because
its valence electron is in the
7th energy level, farthest from the nucleus
Lots of shielding effect which lowers IE and electronegativity.
Atomic radius trends: left to right, top to bottom?
Across a period (left to right), atomic radius decreases.
Down a group, it increases.
Ionization energy trends
Across a period, increases.
Down a group, decreases.
Effective Nuclear Charge.
Zeff=# protons - #shielding electrons.
Core electrons trend across period
Doesn’t. change.
Effective nucleur charge experienced by valence electrons trend across a period?
A valence electron’s experienced Zeff increases, b/c number of protons increases, but shielding effect does not.
Zeff relationship w/ atomic radius?
Each of the following examples has the same number of electrons, but the Zeff changes b/c # of protons differs.
Zeff(F-) = 9 - 2 = 7+
Zeff(Ne) = 10 - 2 = 8+
Zeff(Na+) = 11 - 2 = 9+
So the sodium cation has the largest effective nuclear charge, and thus the smallest radius.
Zeff relationship with atomic radius trend down a group?
Zeff decreases, consequently atomic radius increases.
Cation
A cation (+) (/ˈkæt.aɪ.ən/ kat-eye-ən), from the Greek word κατά (katá), meaning “down”,[7] is an ion with fewer electrons than protons, giving it a positive charge
Cation radii are greater than neutral atom.
True or False?
False. Zeff is greater, therefore atomic radius will be smaller.
Anion
An anion (−) (/ˈæn.aɪ.ən/ an-eye-ən), from the Greek word ἄνω (ánō), meaning “up”,[5] is an ion with more electrons than protons, giving it a net negative charge (since electrons are negatively charged and protons are positively charged).[6]
Atomic radius of an anion is greater than that of the neutral atom.
True or False?
True, More electrons means more shielding, therefore smaller Zeff, therefore greater atomic radius.
Isoelectronic
Having the same # of electrons
Two or more molecular entities (atoms, molecules, or ions) are described as being isoelectronic with each other if they have the same number of electrons[1] or a similar electron configuration[2] and the same structure (number and connectivity of atoms), regardless of the nature of the elements involved.
2 cations, 2 anions, isoelectronic w/ Neon.
- Na+
- Mg2+
- F-
- O2-
Predict the charge of Rb
Rb+
Predict the charge of Cs
Cs+
Predicted Charge:
Ga
At
Se
Ga3+
At-
Se2-
