Regents Chemistry Test Preparation Practice Atom And The Ion

What is the number of electrons in an Al³⁺ ion?*

(1) 10

(2) 13

(3) 3

(4) 16

What occurs when a magnesium atom becomes a magnesium ion?*

(1) Electrons are gained and the oxidation number increases.

(2) Electrons are gained and the oxidation number decreases.

(3) Electrons are lost and the oxidation number increases.

(4) Electrons are lost and the oxidation number decreases.

When an F atom becomes an F⁻ ion, the F atom*

(1) gains a proton

(2) loses a proton

(3) gains an electron

(4) loses an electron

An ion that consists of 7 protons, 6 neutrons, and 10 electrons has a net charge of*

(1) 4−

(2) 3−

(3) 3+

(4) 4+

When lithium reacts with bromine to form the compound LiBr, each lithium atom*

(1) gains one electron and becomes a negatively charged ion

(2) gains three electrons and becomes a negatively charged ion

(3) loses one electron and becomes a positively charged ion

(4) loses three electrons and becomes a positively charged ion

Which Lewis electron-dot diagram represents a fluoride ion?*

(1)

chemical-bonding, atom-and-the-ion, atomic-concepts, valence-electrons, chemical-bonding, electron-dot-diagrams-(lewis-structures), chemical-bonding, electron-dot-diagrams-(lewis-structures) fig: chem62015-exam_g3.png

(2)

(3)

(4)

Compared to a potassium atom, a potassium ion has*

(1) a smaller radius

(2) a larger radius

(3) fewer protons

(4) more protons

Base your answers to questions 8 on the information below.

The atomic radius and the ionic radius for some Group 1 and some Group 17 elements are given in the tables below.

chemical-bonding, atom-and-the-ion fig: chem12012-exam_g13.png

Estimate the radius of a Br ion.*

Base your answers to questions 9 on the information below.

The atomic number and corresponding atomic radius of the Period 3 elements are shown in the data table below.

periodic-table, characteristic-trends fig: chem12013-exam_g16.png

Explain, in terms of electrons, the change in radius when a sodium atom becomes a sodium ion.*

Base your answers to questions 10 on the information below and on your knowledge of chemistry.

The Lewis electron-dot diagrams for three substances are shown below.

chemical-bonding, electron-dot-diagrams-(lewis-structures), atomic-concepts, valence-electrons, chemical-bonding, electron-dot-diagrams-(lewis-structures), chemical-bonding, chemical-bonds, chemical-bonding, bonding-tendency-of-elements fig: chem12016-exam_g7.png

Identify the noble gas that has atoms with the same electron configuration as the positive ion represented in diagram 1, when both the atoms and the ion are in the ground state.*

Base your answers to questions 11 on the information below and on your knowledge of chemistry.

The formulas and names of four chloride compounds are shown in the table below.

atomic-concepts, atomic-models, wave-mechanical-model, chemical-bonding, octet-rule fig: chem12019-exam_g11.png

Explain, in terms of atomic structure, why the radius of a cesium ion in cesium chloride is smaller than the radius of a cesium atom when both are in the ground state.*

Base your answers to questions 12 on the information below.

John Dalton, an early scientist, sketched the structure of compounds using his own symbols for the elements known at the time. Dalton’s symbols for four elements and his drawing of potassium aluminum sulfate are represented by the diagram below.

chemical-bonding, atom-and-the-ion fig: chem62012-exam_g22.png

Today, it is known that the chemical formula for potassium aluminum sulfate is KAl(SO₄)₂\u202212H₂O. It is a hydrated compound because water molecules are included within its crystal structure. There are 12 moles of H₂O for every 1 mole of KAl(SO₄)₂. The compound contains two different positive ions. The gram-formula mass of KAl(SO₄)₂\u202212H₂O is 474 grams per mole.

Identify one positive ion in the hydrated compound. Your response must include both the chemical symbol and charge of the ion.*

Base your answers to questions 13 on the information below and on your knowledge of chemistry.

When magnesium is ignited in air, the magnesium reacts with oxygen and nitrogen. The reaction between magnesium and nitrogen is represented by the unbalanced equation below.

Mg(s) + N₂(g) → Mg₃N₂(s)

Explain, in terms of electrons, why an atom of the metal in this reaction forms an ion that has a smaller radius than its atom.*

Explain, in terms of electrons, why the radius of a potassium atom is larger than the radius of a potassium ion in the ground state.*

Base your answers to questions 15 on the information below and on your knowledge of chemistry.

A sample of seawater is analyzed. The table below gives the concentration of some ions in the sample.

moles-and-stoichiometry, compounds fig: chem62015-exam_g15.png

Compare the radius of an Mg²⁺ ion in the seawater to the radius of an Mg atom.*