Chemistry Year 8 Checkpoint: Chemical Bonding and Structure

Vocabulary flashcards covering atomic stability, ionic bonding, covalent bonding, electronic configurations, and properties of ionic compounds from the Year 8 Chemistry checkpoint review.

Ion

An atom that has lost or gained one or more than one electron, thereby gaining an electrical charge.

Group 8 Elements (Noble Gases)

Elements that have their outermost energy level of electrons completely full, which makes them stable and unreactive so they do not form compounds.

Sodium Ion ($Na^+$)

A positively charged ion with the electronic structure $[2,8]^+$ ($11$ protons and $10$ electrons, giving a $+1$ charge), formed when a sodium atom ($2,8,1$) loses its single valence electron.

Chloride Ion ($Cl^-$)

A negatively charged ion with the electronic configuration of $2,8,8$ ($17$ protons and $18$ electrons, giving a $1-$ charge), formed when a chlorine atom ($2,8,7$) gains one electron to complete its outermost shell.

Ionic Compound

A compound consisting of a regular arrangement of alternating positive and negative ions that are tightly packed together.

Electrostatic Forces of Attraction (Ionic)

Strong forces acting in all directions between oppositely charged positive and negative ions, which hold an ionic compound together.

Giant Lattice Structure

A regular, tightly packed structure formed by thousands of alternating positive and negative ions in an ionic compound.

Melting and Boiling Points of Ionic Compounds

Physical properties that are very high in ionic compounds because lots of thermal energy is required to overcome the strong electrostatic forces acting between oppositely charged ions in the giant ionic lattice.

Electrical Conductivity of Ionic Compounds

A property where ionic compounds conduct electricity only in the molten state or when dissolved in solution, because the ions become free to move and carry a charge.

Solubility of Ionic Compounds

A characteristic property stating that ionic compounds are soluble in water.

Ionic Bonding in Magnesium Oxide ($MgO$)

The transfer of two electrons where a magnesium atom ($2,8,2$) loses two electrons to form a magnesium ion ($Mg^{2+}$, configuration $2,8$) and an oxygen atom ($2,6$) gains two electrons to form an oxide ion ($O^{2-}$, configuration $2,8$).

Ionic Bonding in Calcium Chloride ($CaCl_2$)

The reaction where one calcium atom ($Ca = 2,8,8,2$) loses two electrons to form a calcium ion ($Ca^{2+} = 2,8,8$), and two chlorine atoms ($Cl = 2,8,7$) each gain one electron to form two chloride ions ($Cl^- = 2,8,8$).

Group 1 and Group 7 Reactions

Reactions where alkali metals transfer one electron to halogen non-metals, producing compounds such as lithium chloride, lithium fluoride, potassium chloride, and potassium fluoride.

Covalent Bond

A type of chemical bond formed when non-metal atoms share a pair of electrons to fill their outermost electron shells.

Molecule

A structure consisting of more than one atom joined together.

Dot and Cross Diagram

A diagram where the valence electrons of one atom are represented as dots and the electrons of another atom are represented as crosses to show electron sharing or transfer.

Hydrogen Molecule ($H_2$)

A diatomic covalent molecule formed when two hydrogen atoms, each possessing one electron, share a single pair of electrons so that both attain a full first shell of two electrons.

Hydrogen Chloride Molecule ($HCl$)

A covalent molecule formed when a hydrogen atom (sharing its $1$ electron) and a chlorine atom (sharing $1$ of its $7$ valence electrons) share a single pair of electrons, completing hydrogen's first energy level with $2$ electrons and chlorine's third energy level with $8$ electrons.