Unit 4 Periodic Table Trends

How do atomic radii change down a group?

Radii increase going down a group because as they move down a group they gain an energy level, which increases size.

What happens to atomic radii across a period?

Radii decrease going across a period due to increasing attraction which pulls electrons closer to the nucleus.

What is the trend for cation and anion sizes compared to parent atoms?

Cations are smaller than parent atoms, while anions are larger than parent atoms.

What is ionization energy?

Ionization energy (I) is the energy required to remove the highest energy electron from an atom or ion in its ground state as a gas.

How does ionization energy change across a period?

Ionization energy generally increases going across a period because the nuclear charge of the nucleus is increasing, and the atomic radius is decreasing. These two things increase the pull on the electrons from the nucleus, which makes it require more energy to remove an electron.

How does ionization energy change down a group?

Ionization energy generally decreases going down a group because each new period adds an electron shell, placing the ve- farther from the nucleus, increasing atomic radius, and increasing the shielding by inner electrons, all of which weaken the nuclear attraction.

What is electron affinity?

Electron affinity is the energy change resulting from adding an electron to an atom in its gas phase, which can be positive or negative.

What is the trend for electron affinity across a period?

Electron affinity generally becomes more negative going across a period.(increases)

What are the properties of metals?

Metals are usually shiny, malleable, ductile, and good conductors of heat and electricity.

What are the properties of nonmetals?

Nonmetals are usually dull, brittle, and poor conductors of heat and electricity.

What are metalloids?

Metalloids have characteristics of both metals and nonmetals, such as being shiny yet brittle.

What are noble gases?

Noble gases are nonreactive, monoatomic gases with filled valence shells, making them stable.

What is the trend for electronegativity down a group?

Electronegativity generally decreases going down a group because the size of an atom increases, and the larger size makes it hard for an atom to gain e-.

What is the trend for electronegativity across a period?

Electronegativity generally increases going across a period, because the further right in a period, the closer an element is to gaining noble gas configuration, which means they are more likely to gain e- then loose them.

What is electronegativity?

The ability for an atom to gain electrons.