Chemistry: Module 1 Flashcards
Periodicity
periodicity refers to trends or recurring variations in the properties of elements in the periodic table of elements
Hydroxide (polyatomic ion)
OH-
Sulfate (polyatomic ion)
SO₄²⁻
Sulfite (polyatomic ion)
SO₃²⁻
Carbonate (polyatomic ion)
CO₃²⁻
Ammonium (polyatomic ion)
NH₄⁺
Phosphate (polyatomic ion)
PO₄³⁻
Nitrate (polyatomic ion)
NO₃⁻
Nitrite (polyatomic Ion)
NO₂⁻
Ion
a charged particle that forms during chemical changes when one or more valence electrons transfers from one atom to another
Ionic bond
a bond between metals and nonmetals that bond because one loses electrons and the other gains electrons due to the tendency to FILL VALENCE SHELLS
Cation
Positive ions (elections are lost) ~ usually metals
Anion
Negative ions (elections are gained) ~ usually non-metals
Electrostatic Attraction
The intramolecular force between positively charged particles (e.g. cations) and negatively charged particles (e.g. anions).
Electrostatic attraction exists in structures such as metallic and ionic lattices in which metal cations are electrostatically attracted to anions or a sea of delocalized electrons respectively.
Electronegativity
The energy required for an atom to attract/draw in electron density/electrons with the purpose of filling a valence shell.
Ionisation Energy
The energy required in order to remove an electron from an atom or ion’s valence shell (in order to fill valence shells)
Lattice Structure
A strong (rigid in ionic, malleable in metallic) 3D structure whereby positively charged particles are dispersed with negatively charged particles, held together by a strong intramolecular force: electrostatic attraction.
Simple Covalent Molecular Structure
A simple covalent bond between two or more non-metals to form a molecule. Eg. H₂O & C₂O.
Intermolecular Forces
Forces between independent, identical or unlike molecules in a substance.
Describe the trends in electronegativity down groups and across periods in the periodic table.
Electronegativity:
- Ascends (increases) Across a period →
as the nuclear force gets stronger, pulling
electron density closer to the nucleus of the atom - Decreases Down a group →
as electron shielding increases, reducing the
effect of the nuclear charge on attracting more
electrons.
Describe the trends in ionisation energy within groups and across periods in the periodic table.
Ionization energy (inverse of electronegativity):
- Increases across a period →
as nuclear charge gets stronger upon receiving
more protons whilst keeping the same amount of
electron shielding, it is harder for valence shells
to lose electrons - Decreases down a group →
as more electron shielding is added due to the
increase in electron orbitals, the effect of the
nuclear charge is weakened and is thus easier to
lose electrons in the valence shell.
Giant Covalent Network Structure
A complex system of strong covalent intramolecular bonds that bind non-metals together.
What type of bond is diamond? Can it be limitless?
Diamond is an allotrope and is a giant covalent network. The diamond allotrope can be limitless with a range of different sizes of a diamond.
Does diamond conduct electricity? Explain why or why not?
Diamond cannot conduct electricity because each carbon atom (in an unlimited structure) is bonded to 4 other carbon atoms in a tetrahedral arrangement, there are NO FREE ELECTRONS to allow for a current to pass through.
Does the diamond have a high melting and boiling point? Explain why or why not?
Diamond has very high melting and boiling point as a great deal of heat energy is required to overcome the strong covalent bonds.
Is diamond-hard or soft? Explain why.
Diamond is incredibly hard and brittle as there are strong and stiff covalent bonds holding the covalent network structure together.
What type of bond is graphite? Is it limitless?
Graphite is a giant covalent network structure which is also an allotrope of carbon. It can have an unlimeted amount of graphene laters and can therefore, theoretically, be limitless in structure.
Does graphite conduct electricity? Explain why or why not?
Graphite does indeed conduct electricity, however, only in a horizontal direction.
Does graphite have a high melting and boiling point? Explain why or why not?
Graphite has a high melting and boiling point as there are strong intramolecular covalent bonds that require great amounts of heat energy to overcome.
Is graphite hard or soft? Explain why.
Graphite is soft due to the weak intermolecular forces between each graphene sheet. It can act as a lubricant as the electrons allow for each sheet to slide over each other. However, it is not malleable.
Is graphite malleable or brittle?
Brittle
What type of bond is buckminster fullerene? Is it limitless.
Covalent network structure that exist as seperate molecules and are thus, not limitless networks.
Does buckminster fullerene conduct electricity? Explain why or why not?
Fullerene is a poor conductor of electricity as each carbon atom is bonded with only 3 other carbon atoms, meaning that there are freely moving delocalized electrons. However, as these electrons are contained within the boundaries of a fullerene molecule, there isn’t an effective pathway for current to travel through the structure.
Does buckminsterfullerene have a high melting and boiling point? Explain why or why not?
Fullerene has high melting and boiling points due to the strong intramolecular covalent bonds requiring great heat energy to overcome them.
Is buckminster fullerene hard or soft? Explain why.
Fullerene is hard due to the strong covalent bonds holding the carbon atoms together.
Is diamond malleable or brittle? Explain why.
Diamond is brittle and will shatter. This is due to the strong intramolecular covalent bonds.
Define “Allotropy” and provide an example
Allotropy is the ability for an element to adopt two or more physical forms. These different physical forms (all comprised of the same type of element) are called allotropes.
Some allotropes include:
- Carbon: graphene, graphite, diamond, fullerene
- Oxygen: oxygen, ozone
- Phosphorus: yellow phosphorus, black phosphorus, red phosphorus.
Are allotropes exclusively composed of carbon atoms?
No, there can be oxygen, phosphorus, and a range of other types of elemental allotropes.
Describe the properties of ionic structures
As solid, Ionic structures take form as a strong 3D lattice structure: due to the strong electrostatic attraction between the positively charged cations and the negatively charged anions.
Can’t conduct electricity in solid lattice state: as all anions are bonded to cations, not allowing for a flow of current.
They can only conduct electricity when in molten (l) or aqueous (aq) state: as there are freely moving ions which can conduct electricity.
High melting and boiling points: due to the strong electrostatic attraction between oppositely charged ions which requires great heat energy to overcome and break.
Brittle: as ions can shift and repel against each other when pressure/force is applied to it.
Describe the properties of metallic structures
Strong (electrostatic attraction) 3D lattice structure
Good conductor of electricity: as there is a sea of delocalised and freely moving electrons which allows for the flow of current.
Malleable: as the structure is not rigid and as there are delocalised electrons when force is applied to the lattice structure, electrons can move and maintain their electrostatic attraction to cations; preventing repulsion.
Lustrous: as light can reflect off the sea of electrons.
High melting and boiling points: due to the strong electrostatic attraction between cations and electrons requiring great heat energy to overcome.