C7 Flashcards
(21 cards)
Properties of metal
HIGH DENSITY: the metal ions tightly packed
HIGH MELTING POINT AND BOILING POINT
ELECTRICAL CONDUCTIVITY: the delocalized electrons are able to move within the metallic lattice.
Malleable and ductile: THE METAL Ions can slide past each other without disrupting the metallic bonding
lustrous(shiny): the free electrons cause most metals to be excellent reflectors of most light
THERMAL CONDUCTIVITY: The delocalised electrons transmit the energy of vibration from one ion to its neighbours
Metals forming compounds
React to form positive ions. Cations combine with non metal elements to form ionic compounds
Metals mix with other metals forming alloys
how metals react
metals react by losing valence electrons to form cations
ionic bonding
the loss or gain of electrons.
Between metal and non metal
become stable(full outershell)
covalent bonding
atoms share electrons to become stable
Two non-metals
Physical properties of ionic compounds
High melting and boiling point
Brittle
Don’t conduct electricity in solid state: there are no free particles
Do conduct electricity in aqueous and liquid state: There are free ions allowing the current to flow.
Why does metal have high melting point and boiling point
a large amount of thermal energy is required to overcome the strong metallic bond.
Why do ionic compounds have high melting and boiling points
ionic bonds involve strong electrical attractions between oppositely charged ions and thus require a large amount of thermal energy to be broken
Why are ionic compound brittle
under shearing forces ions of the same charge come closer and their repulsion causes the crystal to shatter.
why is metal thermal conductive
The delocalised electrons transmit the energy of vibration from one ion to its neighbours
Covalent Bonding
Non-metals bond with non-metals electrons are shared so they can both obtain stable octet of electrons
intermolecular bonding two types
Polar molecules- stronger intermolecular force due to dipoles i.g water
non-polar-intermolecular forces increase with size of nucleus
What are the physical properties of covalent network solids?
Very high melting and boiling points, hardness (except graphite), and poor electrical conductivity (except graphite).
What is a covalent network?
A covalent network is a structure where atoms are bonded together in a continuous network entirely by covalent bonds.
Why does diamond have a high melting point?
Because each carbon atom forms four strong covalent bonds in a 3D network, requiring lots of energy to break.
Why can graphite conduct electricity but diamond cannot?
Graphite has free electrons between layers that can move and carry charge; diamond has no free electrons.
Name three common covalent network substances.
Diamond, graphite, and silicon dioxide (SiO₂).
What is a dipole in chemistry, and how does it form?
A dipole is a separation of electrical charge within a molecule due to differences in electronegativity between bonded atoms.
It forms when:
One atom attracts electrons more strongly (more electronegative),
Causing partial charges: δ⁺ on the less electronegative atom and δ⁻ on the more electronegative atom,
Creating a dipole moment
What is a lattice and where is it commonly found?
A lattice is a regular, repeating 3D arrangement of atoms, ions, or molecules.
Common types include:
Ionic Lattice: Found in ionic compounds like NaCl; strong electrostatic forces between oppositely charged ions.
Metallic Lattice: In metals; positive metal ions in a “sea” of delocalized electrons.
Covalent Network Lattice: Found in substances like diamond or quartz; atoms held together by covalent bonds in a continuous network.
Lattices give materials properties like high melting points, hardness, and electrical conductivity (in metals).
What is a hydrogen bond and when does it form?
A hydrogen bond is a strong type of intermolecular force that forms when a hydrogen atom is bonded to a highly electronegative atom (N, O, or F) and is attracted to another electronegative atom nearby.
Key points:
Not a true bond, but stronger than most other intermolecular forces.
Common in water (H₂O), ammonia (NH₃), and hydrogen fluoride (HF).
Responsible for water’s high boiling point and ice’s structure.
