Bonding & Structure in Relation to Properties of Substances Flashcards
What is a covalent bond?
A covalent bond is formed when non-metal atoms share pairs of electrons with each other.
Why do atoms form covalent bonds?
To fill their outer shells to become stable.
What holds covalent bonds together?
The shared electrons are attracted by the nuclei of both atoms.
What diagram is used to show covalent bonding?
A dot-and-cross diagram.
What are the two types of covalent substances?
Simple molecules and giant covalent structures.
What are the properties of simple covalent molecules?
They are usually gases or liquids with low melting and boiling points due to weak intermolecular forces.
Why don’t simple covalent molecules conduct electricity?
They do not have free electrons or ions.
What are the properties of giant covalent structures?
They are solids with high melting and boiling points due to strong covalent bonds.
How is oxygen (O₂) covalently bonded?
Two oxygen atoms share two pairs of electrons, forming a double covalent bond.
How is diamond structured?
Each carbon atom forms four single covalent bonds in a tetrahedral structure, creating a giant covalent structure.
How is graphite structured?
Each carbon atom forms three covalent bonds, creating layers of hexagonal rings.
What is a metallic bond?
A bond where metal atoms share their outermost electrons, creating a “sea of electrons.”
What structure do positive metal ions form?
A lattice, held together by delocalised electrons.
Why are metals shiny, malleable, and ductile?
Due to the mobility of delocalised electrons.
Why are metals good conductors of heat and electricity?
The delocalised electrons move freely and transfer energy.
What are ionic structures, and what are their properties?
Structures formed from ions with high melting points due to strong ionic bonds.
What are metallic structures, and what are their properties?
Structures with high melting points and good conductivity due to delocalised electrons.
What are simple molecular structures, and what are their properties?
Structures with low melting points due to weak intermolecular forces.
What are giant covalent structures, and what are their properties?
Structures with very high melting points due to strong covalent bonds.
