Chapter 25: The Periodic Table

Identify the following elements as metal, nonmetal, or semimetal:

A: Fr -> metal B: Pd -> metal C: I -> nonmetal D: B -> semimetal E: Sc -> metal F: Si -> semimetal G: S -> nonmetal

What is the electron configuration for the outermost electrons of elements found in Group IVB?

s2d2

Arrange the following elements in terms of increasing first ionization energy: Ga, Ba, Ru, F, N

Ba < Ru < Ga < N < F Two common trends should be remembered when ordering atoms according to their ionization energies: 1. The ionization energy increases toward the right across a period because the elements are less willing to give up an electron as the attractive pull (Z eff) of the nucleus increases 2. The ionization energy decreases down a group because the distance separating the valence electrons from the nucleus increases. Therefore, to order the elements according to their first ionization energy, it is necessary to go from the bottom left of the periodic table, where the lowest values are, across to the top right of the periodic table, where the highest values are.

Arrange the following calcium species in terms of increasing size: Ca, Ca+, Ca2+, Ca3+, Ca-, Ca2-

Ca3+, Ca2+, Ca+, Ca, Ca-, Ca2- Positive ions will have smaller radii than the corresponding neutral atoms, and the greater the positive charge, the smaller the ionic radius. Negative ions will have larger radii than the corresponding neutral atoms, and the greater the negative charge, the larger the ionic radius

Which of the following elements has the lowest electronegativity? (choose one) Cesium Strontium Calcium Barium

Cesium: The least electronegative elements are located at the bottom left of the periodic table. Cesium has the lowest Z(eff) so it's the least electronegative. Note that francium (Fr) would be lower still, but it isn't a stable naturally occurring element

The Ca2+ species is electronically similar to the elements in: (choose one) Group IIA Group IA Group IVB Group 0

Group 0: because its outermost valence shell is a complete octet. It is isoelectric to argon

Which of the following elements is most electronegative? S Cl Na Mg

Chlorine has the greatest electronegativity because out of all the choices, it lies farthest to the right and top of periodic table. Chlorine has a great attraction for electrons in a chemical bond because it needs only one more electron to complete a stable octet formation. Therefore it has a high electronegativity.

Which element has the greatest electronegativity? Chlorine Oxygen Sulfur Fluorine

Fluorine. The most electronegative elements are at the top right of periodic table.

Explain why the Group 0 elements are so unreactive

Group 0 elements are also known as the noble, rare, or inert gases. They are very unreactive because their outermost shells contain complete, stable formations. There is no reason for these elements to attempt to gain or lose electrons to other atoms because they are electronically stable on their own

Which group contains an element with an electron configuration of 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6, 4d5, 5s2

Group VIIB: This element has seven electrons in its outermost shell, so its Roman numeral designation is VII; because the d orbital is being filled, it is a nonrepresentative, or B, element. Thus it is found in Group VIIB.

Discuss the properties of metals and give four examples of metallic elements

Meals are shiny, lustrous solids that have high melting points and densities. The ease with which metals lose electrons contributes to their high thermal and electrical conductivities, their malleability and ductility, and the ease with which they form compounds with reactive nonmetals. All of the elements on the left side of the periodic table (except H) and all of the transition elements are metals

Discuss the properties of metalloids and give three examples exhibiting metalloid behavior

Metalloids are elements that possess characteristics of both metals and nonmetals. Their electronic characteristics, such as ionization energies and electronegativities, lie between those of the metals and nonmetals. When undergoing reactions, the metalloids may act as either metals or nonmetals depending upon the species with which they are reacting. The elements classified as metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium.

Arrange the following species in terms of increasing atomic (or ionic) radius: Sr, P, Mg, Mg2+

Mg2+ < P < Mg < Sr - Going from left to right across a period, the atomic radii decrease because the atomic number increases. The increasing number of protons in the nucleus will have a stronger attraction for the outermost electrons, causing them to be held closer and more tightly to a group - positive ions have smaller atomic radii because the loss of electrons leads to a decrease in electron-electron repulsion within the atom, which allows the electrons to move closer to the nucleus

Discuss the properties of nonmetals and give four examples of nonmetallic elements:

Nonmetals are brittle, lusterless elements possessing high ionization energies and high electronegativities. They tend to gain electrons to form negative ions. They are poor conductors of heat and electricity

Discuss the trends in the atomic radii of different elements. How does the atomic number affect the atomic radius of an element?

There are 2 major trends concerning the atomic radii of elements. 1. the atomic radius decreases across the period. 2. atomic radius increases down a group because with every subsequent element down a group, a filled principal energy level has been added. This increases the distance between the nucleus and the valence electrons because orbital size increases with increasing principal quantum number.

The order of the elements in the period table is based on the:

atomic number

Transition metal compounds generally exhibit bright colors because:

because the electrons in the partially filled d orbitals are easily promoted to excited states. The closely spaced d orbitals allow for relatively low energy transitions; these transitions often occur in the visible region of the electromagnetic spectrum, as do other electronic transitions from the transition metal d subshell to other nearby, empty subshells

The change in energy that occurs when an electron is added to an atom is known as the:

electron affinity

The elements within each column of the periodic table:

have similar valence electron configurations

Elements in a given period have the same:

maximum principal quantum number - There are 7 periods, representing the principal quantum numbers n=1 to n=7