Chemistry Chapter 2 Quiz

Atomic Charge and Valence Electrons

• Strontium atom has a charge of +2 due to its position in group 2.
• Maximum charge an ion can typically have is +3.
• The number preceding the letter 'A' in representative elements indicates the number of valence electrons.
• Helium has 2 valence electrons, unlike Magnesium and Silicon, which follow their group number for valence count.

Electron Configuration and Bonding

• Gallium's electron configuration can be determined using the aufbau diagram.
• Halides are negative ions formed when halogen atoms gain an electron.
• The octet rule states that atoms aim for a stable configuration of 8 valence electrons.
• Ionic bonds are formed through the electrostatic attraction between oppositely charged ions.

Ionic Compounds and Conductivity

• Electron dot notation represents valence electrons as dots around the atomic symbol.
• The coordination number is the count of oppositely charged ions surrounding each ion in a crystal.
• Metallic bonds involve the attraction between free-floating valence electrons and positively charged metal ions.

Ionic Characteristics and Reactions

• Salts are neutral ionic compounds.
• Oxygen achieves the octet rule by accepting two electrons for a stable outer level.
• A pseudo noble gas configuration includes 18 electrons in the arrangement of 2 electrons in s, 6 in p, and 10 in d subshells.
• Silver loses 1 electron, and Barium loses 2 electrons to stabilize as ions.

Ion Formation and Types

• The ion formed when potassium achieves noble gas configuration is K+1.
• Both iodine and fluoride gain one electron to form I- and F- ions, respectively.
• Nitrogen gains 3 electrons to achieve a pseudo noble gas configuration.
• Group 1 elements, such as potassium and sodium, form +1 charged ions.

Physical Properties and Crystal Structures

• Ionic compounds generally exist as crystalline solids at room temperature.
• In sodium sulfide, the cation has a charge of +1.
• Ionic compounds are commonly referred to as salts, characterized by electrostatic bonding of positive and negative ions, with nonmetals frequently in the mix.
• Nitrogen transfers 3 electrons to potassium when potassium nitride is formed; typically, nonmetals gain and metals lose electrons during reactions.

Coordination and Metallic Bonds

• In hexagonal close-packed crystals, each atom is surrounded by 12 oppositely charged ions.
• Cesium chloride exhibits a coordination number of 8 in its metallic crystal structure.
• Three types of metallic crystal structures include hexagonal close-packed, face-centered cubic, and body-centered cubic.

Properties of Metals and Alloys

• Metallic bonds allow free-floating electrons to conduct electricity, making metals malleable and ductile.
• Potassium bromide can conduct electricity when melted or disassociated in water.
• Potassium chloride possesses a high melting point due to its ionic nature.
• Metals typically lose electrons, while nonmetals gain them.
• Alloys are preferable as they combine the properties of constituent elements rather than relying on a single element's characteristics.