Chemistry: Atomic Structure, Periodic Table, and Bonding

Vocabulary practice flashcards covering fundamental chemistry concepts including atomic structure, electronic configurations, subatomic particle properties, ions, compound balancing, mass percentage, isotopes, and periodic table trends.

Mass Number

The top number shown alongside a chemical element symbol (such as the $14$ in $^{14}_{\phantom{0}7}\text{X}$), representing the total mass of the atom.

Atomic Number

The bottom number shown alongside a chemical element symbol (such as the $7$ in $^{14}_{\phantom{0}7}\text{X}$), which identifies the number of protons and dictates the order of elements in the periodic table.

Electronic Structure: Group Determination

The principle that the number of electrons in an atom's outermost shell corresponds to the group number of that element in the periodic table.

Electronic Structure: Period Determination

The principle that the total number of occupied electron shells corresponds to the period number of that element in the periodic table.

Ion

An atom that has either gained or lost an electron, resulting in a net electric charge.

Minus Ion

A negatively charged ion formed when an atom gains one or more electrons.

Positive Ion

A positively charged ion formed when an atom loses one or more electrons.

Overall Charge of a Compound

The net electrical charge of any chemical compound, which is always zero; the constituent positive and negative ions must be balanced so there is no net charge (such as $\text{Mg}^{2+} + 2\text{Cl}^- \rightarrow \text{MgCl}_2$).

Mass Percentage

A value that indicates what proportion of a compound is composed of a specific element, calculated as: $\frac{\text{Mass of element in formula}}{\text{Total mass of all atoms in the formula}} \times 100$.

Proton

A subatomic particle located in the nucleus with a relative positive charge ($+$, or positive) and a relative mass of $1$.

Neutron

A subatomic particle located in the nucleus with a neutral charge ($=$) and a relative mass of $1$.

Electron

A subatomic particle situated in shells surrounding the nucleus with a negative charge ($-$) and a relative mass of $0.0005$.

Electrical Neutrality of Atoms

The property of an intact atom having no overall charge because it contains an equal number of positively charged protons and negatively charged electrons.

Isotopes

Atoms of the same element containing the same number of protons (same atomic number) but a different number of neutrons (different mass number).

Relative Atomic Mass ($A_r$) Formula

The mathematical equation used to calculate an element's relative mass taking isotopic abundances into account: $\frac{(\%\text{ abundance of isotope 1} \times \text{mass of isotope 1}) + (\%\text{ abundance of isotope 2} \times \text{mass of isotope 2})}{100}$.

Periodic Table Arrangement

The ordering of chemical elements by increasing atomic number, which naturally arranges elements with similar physical and chemical properties into vertical columns known as groups.

Metalloid

An element found intermediate between metals and non-metals across a period that exhibits properties shared by both metals and non-metals.

Group Trends and Electron Configuration

The principle that elements in the same group share similar chemical properties because they have the exact same number of electrons in their outer shell.

Group 1 Ion Formation

The process where Group 1 atoms lose their single valence electron to form a $1+$ ion, achieving a stable full outer shell.

Group 7 Ion Formation

The process where Group 7 atoms gain one electron to form a $1-$ ion, achieving a stable full outer shell.

Group 7 Reactivity Trend

Reactivity decreases going down Group 7 because the nuclear attraction decreases with distance/shielding, making it harder for the atom to gain an incoming electron.

Group 1 Reactivity Trend

Reactivity increases going down Group 1 because the nuclear attraction decreases with distance/shielding, making it easier for the atom to lose its single outer electron.

Group 1 Reaction with Water

A vigorous reaction where alkali metals react with water to yield an alkaline solution and hydrogen gas.

Group 1 Reaction with Oxygen

A reaction where alkali metals react with oxygen gas to produce a metal oxide, which forms a white solid.

Group 1 Reaction with Chlorine

A reaction where alkali metals react with chlorine gas to form a white powder/precipitate that settles on the sides of the container.

Lithium Reaction Characteristics

Burns with a strongly red-tinged flame to produce a white solid in oxygen; fizzes steadily and gradually disappears in water; produces a white powder settling on the container side in chlorine.

Sodium Reaction Characteristics

Burns with a strong orange flame to produce a white solid in oxygen; fizzes rapidly, melts into a ball, and disappears quickly in water; burns with a bright yellow flame and clouds of white powder in chlorine.

Potassium Reaction Characteristics

Produces a lilac flame (or immediate solid for small pieces) in oxygen; ignites with sparks and a lilac flame while disappearing quickly in water; reacts even more vigorously with chlorine than sodium.

Atomic number

The number located at the bottom of an element's symbol that represents the number of protons in the atom.

Mass number

The number located at the top of an element's symbol representing the total mass of the atom.

Chlorine electronic structure diagram

A shell model with electron configuration $2, 8, 7$, showing $3$ electron shells (indicating Period 3) and $7$ electrons in the outermost shell (indicating Group 7).

Electronic structure (Group relationship)

The number of electrons present in the outermost shell of an atom, which corresponds to the group number the element belongs to on the periodic table.

Electronic structure (Period relationship)

The total number of occupied electron shells an element possesses, which corresponds to the period number the element occupies on the periodic table.

Ion

An atom that has gained or lost one or more electrons, resulting in an electrical charge.

Negative ion (Minus ion)

An ion formed when an atom gains one or more negatively charged electrons.

Positive ion

An ion formed when an atom loses one or more negatively charged electrons.

Compound charge balance

The condition where positive and negative ions combine such that the overall net charge of the compound equals zero.

Mass percentage

A value that indicates what proportion of a chemical compound is made up of a specific element.

Percentage mass formula

$$\text{\% mass of atom } 'x' = \frac{\text{Mass of element } (x) \text{ in formula}}{\text{Total mass of all atoms in the formula}} \times 100$$

Proton

A subatomic particle located in the nucleus with a positive ($+$) charge and a relative mass of $1$.

Neutron

A subatomic particle located in the nucleus with a neutral charge and a relative mass of $1$.

Electron

A subatomic particle found orbiting in shells with a negative ($-$) charge and a relative mass of $0.0005$.

Neutral atom

An atom with no overall charge because it contains an equal number of protons and electrons.

Isotopes

Atoms of the same element that have the same number of protons (same atomic number) but a different number of neutrons (different mass number).

Relative atomic mass ($A_r$) formula

$$A_r = \frac{(\text{\% abundance of isotope 1} \times \text{mass of isotope 1}) + (\text{\% abundance of isotope 2} \times \text{mass of isotope 2})}{100}$$

Groups

Columns in the periodic table containing elements with similar chemical and physical properties because they possess the same number of outer-shell electrons.

Metalloid

Elements found across a period between metals and non-metals that share intermediate properties of both metals and non-metals.

Group 1 ion formation

The process where Group 1 elements lose one outer electron to achieve a full, stable outer shell, forming a $1+$ ion.

Group 7 ion formation

The process where Group 7 elements gain one electron to achieve a full, stable outer shell, forming a $1-$ ion.

Group 7 reactivity trend

Reactivity decreases down Group 7 because the nuclear attraction decreases with distance, making it harder to attract and gain an incoming electron.

Group 1 reactivity trend

Reactivity increases down Group 1 because the attraction from the nucleus decreases, making it easier to lose the single outer electron.

Group 1 metals (Alkali metals)

Metals characterized by a single outer electron that react vigorously with water to produce an alkali solution and hydrogen gas.