Locate aluminum in the periodic table and give its group number and period number.

How many electrons are present in an atom in which the first and second shells and the 3s subshell are filled? Name the element.

An element has completely filled n = 1 and n = 2 shells and has six electrons in the n = 3 shell. Identify the element and its major group (i.e., main group, transition, etc.). Is it a metal or a nonmetal? Identify the orbital in which the last electron is found.

For chlorine, identify the group number, give the number of electrons in each occupied shell, and write its valence-shell configuration.

Use the following blank periodic table to show where the elements matching the following descriptions appear.

a. Elements with the valence-shell electron configuration ns² np⁵

b. An element whose third shell contains two p electrons

c. Elements with a completely filled valence shell

Use the following orbital-filling diagram to show the electron configuration for As:

How do atoms of different elements differ?

Find the mass in atomic mass units of the following:

a. 1 O atom, with a mass of 2.66 × 10^-23 g

b. 1 Br atom, with a mass of 1.31 × 10^-22 g

How many O atoms of mass 15.99 amu are in 15.99 g of oxygen?

Where within an atom are the three types of subatomic particles located?

Why does the fourth period in the periodic table contain 18 elements?

Answer the following questions for the elements from cerium through lutetium:

a. Are they metals or nonmetals?

b. To what general class of elements do they belong?

c. What subshell is being filled by electrons in these elements?

What is the total number of orbitals in the third shell? The fourth shell?

How many subshells are there in the third shell? The fourth shell? The fifth shell?

Use arrows to show electron pairing in the valence p subshell of

a. Sulfur

b. Bromine

c. Silicon

What is the mass (in amu and in grams) of a single atom of Carbon-12?

What is the mass (in grams) of 6.02 × 10²³ atoms of Carbon-12?

An unidentified element is found to have an electron configuration by shell of 2 8 18 8 2. To what group and period does this element belong? Is the element a metal or a nonmetal? How many protons does an atom of the element have? What is the name of the element? Write its electron-dot symbol.

What is wrong with the following electron configurations?

a. Ni 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰

b. N 1s² 2p⁵

c.

d.

Look again at the trends illustrated in Figures 2.3 and 2.4.

a. How do the peaks/valleys correlate with locations in the periodic table?

b. Are there other chemical properties that also exhibit periodic trends? What are they?

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