Honors Pre-AP Chemistry: Periodic Trends and Element Classification

Who is known as the Father of the Periodic Table?

Dmitri Mendeleev

What year did Mendeleev publish his Periodic Table?

1869

What did Mendeleev use to organize the elements in his table?

Increasing atomic mass and similar properties

What significant prediction did Mendeleev make about missing elements?

He predicted the existence of 10 new elements, 7 of which were eventually discovered.

What did Henry Moseley contribute to the Periodic Table in 1913?

He rearranged the elements by increasing atomic number.

What is the Periodic Law?

When elements are arranged in order of increasing atomic number, there is a periodic pattern in their physical and chemical properties.

What elements did Glenn Seaborg discover?

Elements 94-102, including plutonium, americium, and seaborgium.

What change did Seaborg make to the Periodic Table?

He moved the actinides and lanthanides below the main body of the table.

What are the horizontal rows of the Periodic Table called?

Periods

What are the vertical columns of the Periodic Table called?

Groups or families

What is the significance of elements in the same group?

They have similar properties.

What happens to an atom when it loses electrons?

It becomes a positively charged ion (cation).

What happens to an atom when it gains electrons?

It becomes a negatively charged ion (anion).

What is meant by 'isoelectronic'?

Having the same number and arrangement of electrons.

What is the electron configuration of Na+?

[Ne]

How are cations formed from transition metals?

Electrons are removed first from the ns orbital and then from the d orbitals.

What is metallic character?

The level of reactivity of a metal.

Why is sodium considered a very reactive metal?

It readily loses one electron to form a positive ion.

What is the electron configuration of Copper(I) Ion?

[Ar]3d10

What is the electron configuration of Copper(II) Ion?

[Ar]3d9

What are the outermost electrons in the electron configuration?

They are in the outermost principal energy level.

What is the significance of the lanthanides and actinides in the periodic table?

They are often referred to as inner transition elements.

What did Mendeleev leave in his periodic table for missing elements?

Spaces for missing elements.

What is the atomic number of seaborgium?

106

What is the electron configuration of F-?

1s22s22p6 or [Ne]

What is the electron configuration of O2-?

1s22s22p6 or [Ne]

What is the electron configuration of N3-?

1s22s22p6 or [Ne]

What are the groups numbered in the periodic table?

1-18

What are the periods numbered in the periodic table?

1-7

What is the nuclear charge of an atom?

The total charge of all the protons in the nucleus, equal to the atomic number.

How does nuclear charge change across the periodic table?

Nuclear charge increases as you move across a period and down a group.

What is atomic radius?

Half of the distance between the nuclei of two touching atoms.

What trend is observed in atomic radius across a period?

Atomic size decreases from left to right due to increased nuclear charge.

What trend is observed in atomic radius down a group?

Atomic size increases as you move down a group due to more occupied energy levels.

What is the shielding effect?

Inner electrons block the attraction from the nucleus, reducing the effective nuclear charge felt by outer electrons.

How do cations compare in size to their neutral atoms?

Cations are always smaller than the neutral atom from which they are made.

What happens to the size of cations as more electrons are lost?

The more electrons lost, the smaller the ion becomes.

How do anions compare in size to their neutral atoms?

Anions are always larger than the neutral atom from which they are made.

What happens to the size of anions as more electrons are gained?

The more electrons gained, the bigger the ion becomes.

What are isoelectronic species?

Species with the same number of electrons.

How does ionic radius change within an isoelectronic series?

Ionic radii decrease with increasing atomic number due to increasing nuclear charge.

What is electronegativity?

The tendency for an element to attract electrons when chemically combined with another element.

Which element has the highest electronegativity?

Fluorine, with a value of 4.0.

What is the trend in electronegativity down a group?

Electronegativity decreases moving down a group.

What is the trend in electronegativity across a period?

Electronegativity increases moving from left to right across a period.

What is ionization energy?

The amount of energy required to remove an electron from a gaseous atom.

How does ionization energy change down a group?

Ionization energy decreases down a group due to increased distance from the nucleus.

How does ionization energy change across a period?

Ionization energy increases across a period due to increased effective nuclear charge.

What is electron affinity?

The energy change associated with the addition of an electron to an atom in the gaseous state.

What is the trend in electron affinity across a period?

Electron affinity tends to increase across a period.

What is the trend in electron affinity down a group?

Electron affinity tends to decrease as you go down a group.

What is a major exception to the trend in electron affinity?

The electron affinities of elements B through F are less negative than those of elements immediately below them due to increased electron-electron repulsions.

What is the general trend in metallic behavior?

Metallic behavior increases down a group and decreases across a period.

What are diagonal relationships in the periodic table?

Similarities between pairs of elements in different groups and periods due to closeness of charge densities.