Foundations in chemistry Flashcards
What is the real active mass of an electron proton and neutron
Proton is 1
Neutron is 1
Electron is 1/1836
What is an isotope
Atoms of the same element with the same number of protons but a different number of neutrons
What is relative isotopic mass
Mass of an atom of an isotope compared with 1/12th mass of carbon 12
What is relative atomic mass
Weighted mean mass of an atom of an element compared with 1/12th mass of carbon 12
How many electrons are on each shell
1 has 2 electrons
2 has 8 electrons
3 has 18 electrons
4 has 32 electrons
What is a orbital
A region of space around the
Nucleus that can hold two electrons with paired spins
What orbitals do each energy levels have
1st has only s
2nd has s and p
3rd has s , p and d
4th has s , p , d and f
How many orbitals do each sub shell have
S has 1
P has 3
D has 5
F has 7
Why do electrons in the same orbital get drawn as oppositely facing arrows
The negative electrons repel each other and it also indicated the electrons spin
What is the electron configuration of carbon
1s2 2s2 2p2
how to write short hand electron configuration
replacing orbitals with the most recent preceding noble gas’s known electron configuration
what is the shorthand configuration of chlorine
[Ne]3s²3p5
what are the noble gas facts
full valence electron shells
monoatomic non metal gases at room temp
very stable
high ionising energies
do not combust
low bp
what is ionic bonding
electrostatic attraction between oppositely charged ions
what happens to electrons in ionic bonding
they are transferred
what is a covalent bond
shared pair of electrons
What is a dative covalent bond
when a shared pair of electrons that have been donated by only of the bonded atoms for example NH4
What groups can break the octet rule
5-7
In double and triple covalent bonds all atoms have the structure of the…
Nearest noble gas
How is expanding the octet possible
In the. 3rd shell when a d sub shell becomes available
How do dative covalent bonds usually occur
When a compound reacts with a H+ ion
What is the name and bond angle of a covalent molecule with 2 electron pairs
Linear
180
What is electron repulsion theory
The shape of a molecule is determined by the number of electron pairs as electrons repel each other
What is the name and bond angle of a molecule with 3 electron pairs
Triagonal planar
120
What is the name and bond angle of a molecule with 4 electron pairs
Tetrahedral
109.5
What is the name and bond angle of a molecule with 5 electron pairs
Trigonal bipyramidal
120/90
What is the name and bond angle of a molecule with 6 electron pairs
Octaheadral
90
What is the name and bond angle of a molecule with 1 lone pair
Pyramidal
107
What is the name and bond angle of of a molecule with 2 lone pairsb
Non linear
104.5
what is electronegativity
A measure of the ability of an atom to attract a bonding pair of electrons in a covalent bond
What are examples of very electronegative elements
oxygen, florine, chlorine, nitrogen etc
what are factors affecting electronegativity
atomic charge
distance from the nucleus
electron shielding
what is a HCl bond known as
polar covalent bond
what must a molecule be for it to be polar
asymmetrical
what does a polar molecule form
a dipole
why are symmetrical molecules non polar
the dipoles cancel each other
do lone pairs cause symmetrical or asymmetrical molecules
asymmetrical
what is an intermolecular force
an attractive force between neighbouring molecules
what are the 3 types of intermolecular forces
-permanent dipole-dipole interactions
-london forces
-hydrogen bonds
what is the strongest and weakest intermolecular force
hydrogen is strongest
london in weakest
explain a permanent dipole force
-Its a weak attractive force between permanent dipoles in neighbouring polar molecules
-The permanent dipole of one molecule attracts the permanent dipole of another
explain london forces
-They act between all molecules, whether they are polar or non polar
-Electrons might find themselves towards one side of the molecule because they are mobile, forming a temporary dipole
-This creates induced dipoles which are attracted to the temporary dipoles
explain hydrogen bonding
-Electrostatic forces of attraction between a proton deduced of electrons attached to an electronegative atom and the lone pair of another electronegative atom
why is ice less dense as a solid
the hydrogen bonds hold the H2O molecules in an open lattice shape as a solid, bit as they melt the molecules move closer together
what elements does hydrogen bonding happen to with hydrogen
Nitrogen, Oxygen and Florine
What is metallic bonding
The electrostatic attraction between positive metal ions and delocalised electrons
What are the properties of giant metallic lattices
High mp and bp
Good electrical conductors
Malleable and ductile
What do giant metallic lattices have high melting points and boiling points
Strong electrostatic attraction between positive metal ion and delocalised electrons which require a lot of energy to overcome
Why are giant metallic lattices good electrical conductors
Delocalised electrons are free to move and carry a charge
Why are giant metallic lattices malleable and ductile
The ions are able to move past each other into new positions whiteout breaking metallic bonds
What is an alloy
A mixture of metals
what is an ionic lattice
regular repeating pattern of oppositely charged ions
what are the properties of ionic compounds
-Conductors when molten
-High mp and bp
-Soluble in polar solvents
explain why ionic lattices are conductors when molten
ions are free to move through the structure
explain why ionic lattices have high melting and boiling points
electrostatic attraction between oppositely charged ions is so strong large amounts of energy are needed to overcome
what can increase electrostatic attraction in ionic compounds/lattices
higher ion charge
explain why ionic lattices are soluble in polar solvents
polar molecules break down the lattice by surrounding each ion to form a lattice; positive ion in solvent to negative ion in lattice, and negative ion in solvent to positive ion in lattice
What are properties of simple molecular substances
-weak and soft when solid due to intermolecular forces
-don’t conduct electricity as not charged
-soluble in non polar solvents because London forces form between the solvent and molecule
what are the differences between graphite and diamond
graphite can conduct electricity but diamond cannot
