Bonding and Structure Flashcards
Define ionic bonds
Ionic bonds are strong electrostatic forces of attraction between oppositely-charged ions
If in lattice of positive ions and negative ions, each positive ion(Y) is surrounded by eight negative ions and each negative(Z) surrounded by 4 positive ions, what is formula of compound
YZ2
Why does sodium chloride have high melting points
Sodium chloride has giant ionic structure, large amount of energy required to overcome strong electrostatic forces of attraction between oppositely-charged ions
Why does magnesium oxide have much higher melting point than sodium chloride?
(State charges of all ions)
Due to the greater charges, more energy is required to overcome the stronger electrostatic forces of attraction between magnesium ions and oxide ions compared to those between sodium ions and chloride ions
Why does hydrogen chloride not conduct electricity in solid state
Oppositely-charged ions are held in fixed positions by strong electrostatic forces of attraction between oppositely-charged ions. Ions are not free-moving and cannot conduct electricity
Why does aqueous hydrogen chloride conduct electricity
Strong electrostatic forces of attraction between oppositely-charged ions have been overcome. Ions are free-moving and can conduct electricity
State solubility of ionic compounds in water and organic solvent
Soluble in water and insoluble in organic solvent
Define electronegativity
Electronegativity refers to ability of atom to attract a shared pair of electrons towards itself in covalent bond
Which element is the most electronegative
Fluorine
What happens when two atoms involved in covalent bond have same or similar electronegativity
A non-polar covalent bond results and two atoms have equal pull on shared pair of electrons
What happens when two atoms involved in covalent bond have different electronegativity values
Pair of shared electrons not equally shared and polar covalent bond results. More electronegtative atom acquires partial negative charge and less electronegative atom acquires partial positive charge
Why does methane have low melting point
Has simple molecular structure, small amount of energy is required to overcome weak intermolecular forces of attraction
Why is methane a non-conductor of electricity
Methane has a simple molecular structure, there are no free-moving valence electrons available to conduct electricity
State solubility of simple molecules in water and organic solvent
Insoluble in water and soluble in organic solvents
Define allotrope
Different forms of same element, allotropes may have different properties such as hardness or electrical conductivity
State structure of diamond
A giant molecular structure, each carbon atom is covalently bonded to four other carbon atoms in a tetrahedral arrangement
Why does diamond have very high melting point
Has giant molecular structure, large amount of energy is required to break strong covalent bonds between carbon atoms.
Why does diamond not conduct electricity
Has giant molecular structure, all four valence electrons of each carbon atom are used for covalent bonding, no free-moving valence electrons present to conduct electricity
Why is diamond hard
All carbon atoms are held by strong covalent bonds throughout the structure
Why does graphite have high melting point
Graphite has giant molecular layered structure, a large amount of energy is required to overcome the strong covalent bonds between the carbon atoms
Why does graphite conduct electricity
Each carbon atom uses three out of four valence electrons in bonding, valence electrons not used in bonding are free-moving to conduct electricity
Why is graphite soft and slippery
Has giant molecular layered structure, layers of carbon atoms in graphite are held by weak intermolecular forces of attraction and can slide over one another when force is applied
Define metallic bond
Strong electrostatic forces of attraction between positive metal ions and ‘sea’ of delocalised free-moving valence electrons
Why do metals have high melting point
Metal has giant metallic structure, large amount of energy needed to overcome strong electrostatic forces of attraction between positive metal ions and ‘sea’ of delocalised free-moving valence electrons
Why can metals conduct electricity
Metals has giant metallic structure, has a ‘sea’ of free-moving valence electrons present to conduct electricity
Why are metals ductile and malleable
Metals have giant metallic structure, they are arranged orderly in layers and when force is applied layers of metal ions can slide over one another
