Wk 3_3: Mock Quiz : Atomic Structure, Formulas & Mass Numbers (Diagnostic Tool): CHEM-105 Introduction To Chemistry

Which subatomic particles are found in the nucleus of an atom?

Protons and neutrons are located inside the nucleus, while electrons orbit around the outside of the nucleus.

What is the correct chemical symbol for sulfur?

$\text{S}$ ($\text{Na}$ is sodium, $\text{Sc}$ is scandium, and $\text{Si}$ is silicon).

Which element has the atomic number $14$?

Silicon ($\text{Si}$) has the atomic number $14$.

How many protons are present in a neutral atom of chromium?

Chromium ($\text{Cr}$) has an atomic number of $24$, which means it has $24$ protons.

An atom of sodium has $11$ protons, $12$ neutrons, and $11$ electrons. What is its mass number?

The mass number is $23$ ($\text{Mass Number} = \text{Protons} + \text{Neutrons} = 11 + 12 = 23$).

An atom has $15$ protons and $16$ neutrons. What is its correct isotope symbol?

Phosphorus-31 ($^{31}\text{P}$), because $15$ protons identify the element as Phosphorus and the mass number is $15 + 16 = 31$.

Which type of element is chlorine?

Chlorine is classified as a nonmetal (specifically a halogen) located on the right side of the periodic staircase.

Which element has chemical properties and reactivity most similar to sodium ($\text{Na}$)?

Potassium ($\text{K}$), because elements in the same vertical column (Group 1A - Alkali Metals) share similar chemical reactivity.

How many total oxygen atoms are present in one formula unit of calcium hydrogen carbonate, $\text{Ca}(\text{HCO}_3)_2$?

$6$ oxygen atoms (the subscript $2$ outside the parentheses doubles everything inside: $3 \times 2 = 6$).

How many total atoms of all elements combined are in one formula unit of aluminum sulfate, $\text{Al}_2(\text{SO}_4)_3$?

$17$ total atoms ($2$ aluminum + $3$ sulfur + $12$ oxygen = $17$).

An ion of calcium has $20$ protons and $18$ electrons. What is its chemical symbol and charge?

$\text{Ca}^{2+}$ (protons $+20$ minus electrons $-18 = +2$ net charge).

Which of the following elements exists in its natural state as a diatomic molecule: $\text{Ca}_2$, $\text{Mg}_2$, $\text{N}_2$, or $\text{Al}_2$?

$\text{N}_2$ (Nitrogen is one of the $7$ diatomic elements).

What seven elements naturally exist as diatomic molecules?

Bromine ($\text{Br}_2$), Iodine ($\text{I}_2$), Nitrogen ($\text{N}_2$), Chlorine ($\text{Cl}_2$), Hydrogen ($\text{H}_2$), Oxygen ($\text{O}_2$), and Fluorine ($\text{F}_2$), remembered by BrINClHOF.

Why is $\text{NH}_4\text{Cl}$ classified as an ionic compound?

It contains the ammonium polyatomic cation ($\text{NH}_4^+$) and chloride anion ($\text{Cl}^-$).

What is the correct chemical formula for iron(III) oxide?

$\text{Fe}_2\text{O}_3$ (Iron(III) has a $+3$ charge and oxide has a $-2$ charge; balancing gives $2(+3) + 3(-2) = 0$).

What is the correct chemical name for $\text{Na}_2\text{O}$?

Sodium oxide (Sodium is a Group 1 metal with a fixed charge, so no Roman numerals or Greek prefixes are used).

What is the correct chemical name for $\text{CuCl}_2$?

Copper(II) chloride (Two chloride ions total $-2$, so copper must have a $+2$ charge to balance, forming $\text{Cu}^{2+}$).

What is the correct chemical name for the molecular compound $\text{P}_2\text{O}_5$?

Diphosphorus pentoxide (Greek numerical prefixes di- = $2$ and penta- = $5$ are used for compounds of two nonmetals).

What is the correct chemical name for the acid $\text{HCl}(aq)$?

Hydrochloric acid (Binary acids use the prefix hydro- and suffix -ic acid).

What chemical element is represented by the symbol $\text{Na}$?

Sodium

What chemical element is represented by the symbol $\text{Sc}$?

Scandium

What chemical element is represented by the symbol $\text{Si}$?

Silicon

How do you name a binary ionic compound formed from a Group 1 metal and a nonmetal?

Name the metal followed by the nonmetal with an -ide ending, without using Roman numerals or Greek prefixes.

How are binary acids consisting of hydrogen and a single nonmetal named in aqueous solution?

Use the prefix hydro- and the suffix -ic acid attached to the nonmetal root name.

What is the standard ionic charge on a chloride ion?

$-1$ ($\text{Cl}^-$)