Module 2,electrons, Bonding And Structure Flashcards
Compound
A substance that is composed of 2 or more different elements
Molecule
A group of atoms bonded by the covalent bonds, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction. Can be element or a compound.
Ion
An atom or molecule with a net charge due to loss/gain of electrons
Molecular ion
An ion made up of a group of atoms with an overall charge(usually by gaining/losing a monatomic ion like H+)
Monoatomic ion
Formed by gain/loss of electrons in a single atom e.g cl-
Iodide
I-
Ammonium
NH4+
Hydroxide
OH-
Fluoride
F-
Carbonate
CO3 2-
Nitrate
NO3 -
Sulphate
SO4 2-
Lithium ion
Li+
Aluminium ion
Al3+
Chloride
Cl-
Hydrogen carbonate
HCO3 -
Calcium ion
Ca2+
Copper (ii) ion
Cu2+
Hydrogen ion
H+
Magnesium ion
Mg2+
Silver(i) ion
Ag+
Phosphate
PO4 3-
How many electrons in s, p, d, f sub shell
S-2 p-6 d-10 f-14
How many electrons in each orbital
2
Notation for electron shells
3s, 3 represents its in the 3rd shell, s is type of sub shell
Describe electron shells
Electrons have fixed energies. Move in shells/energy levels. Each shell has a number, n (principle quantum number), further from nucleus, higher its energy.
Orbital
An area in an atom which can hold 2 electrons. Orbitals in different sub shells have different shapes
What is spin
A property electrons have, to do with momentum. 2 electrons in same orbital will have opposite spins, one is up the down. Electrons occupy orbitals in same energy level singly first, before they pair up.
Why does the 4s shell fill up before 3d
4s has lower energy than 3d
What is the aufbau principle
Electrons fill up lowest energy sub shells first, closest to nucleus.
EQ- Complete the electron configuration of a silicon atom
1s2 2s2 2p6 3s2 3p2
EQ- how many full orbitals are in an atom of sulfur
Draw out the arrows in boxes, then count how many have 2 electrons in, the answer is 7
Electron arrangement of bromine
Look at atomic number, 35, 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5, short structure, look at previous group 8, [Ar]4s2 3d10, then look at structure of that group 8 and add anything to next to [Ar] that is not in Ar for example
What determines what element is where in the periodic table
N of electrons in outer shell, group principle quantum number, period outer most electron orbital, block
What is the shape if p and s sub shells
S are spherical, cross with diagonal line and circle in middle. P have dumbbell shapes
What is Heisenberg uncertainty principle
Cannot know speed of electrons and exact position, orbitals are where most likely found but not definitely
Metallic bonding
Strong electrostatic attraction between positive metal ions and delocalised electrons
Ionic bonding
Strong electrostatic attraction between oppositely charged ions
Covalent bonding
Strong electrostatic attraction between a shared pair of electrons and positive nuclei
What are the properties of a metallic structure
Malleable, ductile, conducts electricity, high mp/bp
What are the properties of a ionic structure
High mp/bp-due to strong electrostatic forces, conducts electricity when l and aq not s, soluble
What are the properties of simple molecule structure
Low mp/bp, can’t conduct electricity
What are the properties of a giant covalent lattice
Brittle/soft, high mp/bp, can’t conduct electricity
What are the properties of diamond
Hard/strong, high mp/bp, doesn’t conduct electricity as it uses all 4 electrons
Ocet rule
Atoms will share or transfer electrons until they have a full outer shell of 8 electrons
What are the exceptions to the ocet rule
D block elements, p block elements in 3rd row and below, some p blocks can have less than 8
Dative covalent bonding
Both electrons come from one atom
Describe electron density and lone pairs
Electrons repel each other. Electrons exist in area of electron density, 2 types bonding and lone(a pair of electrons not involved in bonding). Single bond counts as 1 electron density and double/triple bond counts as 1 area of electron density. Lone pairs count as area of electron density but repel more than a bonding pair
Which pair repel the most to least
Most- lone and bonding, lone and lone, bonding and bonding-least
How to see how many bonding and lone pairs
Draw Dot and cross diagram
Describe intermolecular forces
Forces between molecules, weaker than covalent/ionic/metallic. Determine mp/bp, van der walls(old term for intermolecular forces, don’t use)
Describe London forces
Induced dipole-dipole forces, electron move constantly and randomly within an atom, uneven distribution of electrons causes instantaneous dipole, dipole induces a dipole in neighbouring molecule. Simplified-electrostatic force of an attraction between s- on one atom and s+ on other atom of another molecule. More electrons in a molecule, greater possible difference in distribution of electrons, stronger induced dipoles, stronger London forces.
Why does bp of group 7 increase down group
More electrons in a molecule, greater possible difference in distribution of electrons, stronger induced dipoles, stronger London forces.
Describe permanent dipole-dipole interactions
Only between polar molecules, stronger than London forces.
Describe hydrogen bond relevant to intermolecular forces
Only when hydrogen is covalently bonded to F,N,O (very electronegative) resulting in a very polar bond. Between H and lone pair in another molecule. Much stronger than London forces or permanent dipole interactions. Molecules able to form hydrogen bonds, can dissolve in water, higher bp/mp.
Why is ice less dense than water
Due to hydrogen bonds formed, molecules form an open lattice structure
EQ- why does ice have a higher melting point than solid ammonia
Ice has stronger hydrogen bonds, O has 2 lone pairs, N has 1(look at dot and cross diagram)
EQ- Why do at RTP alcohol are liquids whereas alkanes are gases
Alkanes have intermolecular forces, alcohols have hydrogen bonds and intermolecular forces, hydrogen bonds stronger
EQ- why does NF3 have a permanent dipole
Is pyramidal, dipoles do not cancel out, F more electronegative than N
EQ- why does SF6 have a octahedral shape
because it has 6 bonding and 1 lone, electrons repel as far as they can
What to include in a extended answer about shape of molecules
Electrons group repel as far as possible, number of electron density, number of bonding/lone pairs, lone pairs repel more than bonding, this causes shape… with bond angle of…
Electronegativity
A measure of the ability of an atom in a molecule to attract electrons in a chemical bond
What 2 factors affect electronegativity
Radius-smaller than radius of atom, greater attraction to the bonded pair of electrons(less distance between electrons and positive nuclei, stronger attraction). Nuclear charge-greater nuclear charge, stronger attraction.
Describe polar bond
2 atoms bonded have different electronegativity’s, has dipole negative and positive side. Has polar bonds and no symmetry or symmetry but doesn’t cancel out charges.
Describe non-polar bond
2 atoms bonded have same/similar electronegativtys. No polar bonds,or there is symmetry.
What is the most electronegative
Fluorine
What is the order of sub shells
1s,2s,2p,3s,3p,4s,3d,4p,4d
What does electronegativity mean
The ability of an atom to attract the electrons in a covalent bond
