Module 1 Yr 11 Flashcards

Question

Trends in periodic table

Answer 1

Groups I-III, reactivity increases downwards Groups V-VII, reactivity decreases downwards Most reactive elements: (Bottom Left (Caesium & Francium)) & (Top right (Fluorine and Chlorine)) Bigger the atom, more reactive due to larger atomic radius Rules don’t apply to transition metals due to them being semimetals Across period, electronic configuration of atom contains one more valence electron than previous. Down group, one more principle quantum shell is added to electronic configuration.

Answer 2

Atomic number > 83 Neutron to proton ratio is not within the zone of stability

Answer 3

Stable neutron to proton ratio is approximately 1:1 for elements 1-20 1.3:1 for elements 21-50 1.5:1 for elements 51-83 B- decay is above band of stable nuclei B+ decay is below band of stable nuclei Alpha decay is above zone of stability

Answer 4

Alpha decay: the release of alpha particles (helium nuclei) from nucleus Helium nuclei has 4 mass number and atomic number of 2 Likely to be emitted from nucleus when too large (atomic number > 83)

Answer 5

Occurs when neutron to proton ratio is too low Proton changes to neutron and positron where latter is emitted nucleus has 0 mass no and -1 atomic no Whilst: Neutron in the nucleus changes into a proton and an electron where latter is eliminated Process occurs when neutron to proton ratio is too high nucleus has 0 mass no and 1 atomic no

Answer 6

The emission of gamma rays. Occurs when nucleus is in an excited state and gamma ray release brings it back to stability

Answer 7

Ionising power: the ability to remove electrons from an atom producing an ion. The ability of radiation to harm humans is a result of ionising power.

Answer 8

Alpha (+2): Low pp, high ip Beta- (-1): Medium pp and ip Gamma (0): High pp and low ip

Answer 9

Fusion: process when two small nuclei combine forming a larger nucleus (more expensive due to large energy need to power it) Fission: process when one large nucleus splits to form two or smaller nuclei

Answer 10

Principle quantum number: Are orbitals in every principle electron shell. Orbitals are described by which principle level it occupies Shape: Orbitals can take the shape of a sphere (s orbital), hourglass (p orbital), cloverleaf (d orbital) and even more complex (f orbital) Orientation: point in different directions

Answer 11

Heisenburg’s uncertainty principle states one cannot determine with certainty the exact position and velocity of an electron

Answer 12

States that no two bound electrons within one atom can have the same set of four quantum numbers.

Answer 13

electrons fill lower-energy atomic orbitals before filling higher-energy ones

Answer 14

Every orbital in a sublevel is singly occupied before any orbital is doubly occupied.

Answer 15

If a species is excited by quanta (packets of energy of specific size), electrons can jump from lower energy level to higher energy level. An excited species can violate the aufbau principle and hund’s rule but must obey Pauli’s exclusion principle

Answer 16

Used to identify presence of certain cations since a distinctive colour is produced when an ionic solution containing that cation is placed into a flame. When solution is placed in flame, metal cations are atomised. Visible light created when electrons transition to higher energy level due to heating, electrons lose energy and relaxes to original energy level, em radiation in form of visible light is released Not all metals have a flame test colour in visible range. Colour produced depends on the difference in energy between energy levels

Answer 17

Lithium: Red Sodium: Yellow-orange Potassium: Lilac Calcium: Brick-red Barium: Apple green Strontium: Red Copper: Blue-green

Answer 18

Absorption spectrum: Produced when white light passes through cool gaseous sample of an element with element absorbing specific wavelengths of that light Emission spectrum: Produced when a gaseous sample of an element is heated. Causes excitation & de-excitation of electrons, with de-excitation releasing energy in the form of photons. Correspond to specific wavelengths of light (spectral lines).

Answer 19

Electrons are in stationary states, don’t emit em radiation. Electrons exist at discrete energy levels with transitions between energy levels caused by absorption or release in energy. Absorption spectrum of hydrogen can be explained in terms of electron between specific energy levels.

Answer 20

Proposed electrons behave like waves and particles. Electrons don’t orbit, energy and mass is spread out over region (orbital)

Answer 21

Effective Nuclear Charge: The net positive charge experienced by electrons. =to the charge of the nucleus subtracted by no of shielding electrons.

Answer 22

Atomic radius, IOE1 and electronegativity Zeff increases across period due to charge of nucleus increasing due to increased no of protons whilst the no of shielding inner electrons remain constant due to the no of shells remaining the same Zeff increases down the group as even though the no of shielding inner electrons increases, the effect of shielding diminishes with increased electron shells. Whilst this occurs, the charge increases due to the increased no of protons in the nucleus.

Answer 23

Total distance from atomic nucleus to the outermost occupied electron orbital. Down group, Ar increases due to increased atomic number meaning there are more protons in the nucleus and the zeff on all electrons including valence electrons have increased. Electrons are drawn together to the nucleus due to a stronger electrostatic force causing the atom size to shrink. Across period, Ar decreases The zeff on valence electrons increases as down the group, the valence electrons occupy higher energy energy shells due to an increased principal quantum number consequently causing an increased distance away from nucleus

Answer 24

First ionisation energy: energy required to remove an outer valence electron from an element in its gaseous state. Prior to measurement, element must be vaporised. It increases across period due to the number of protons increasing causing a greater zeff making it more strongly bound. Thus more energy is required to remove the electron. Decreases down the group due to increased atomic radius as the highest energy valence electron is further away from nucleus causing less energy to be put to remove the electron.

Answer 25

A measure of tendency of an atom in a compound to attract shared electrons towards itself. Elements on left side have low electronegativity as they want to lose electrons to attain noble gas configuration. Elements on right side have high electronegativity as they want to gain electrons to achieve stability Across period, it increases as increased no of protons in nucleus increases Zeff. A stronger zeff results in a greater electrostatic attraction with electrons increasing element's electronegativity. Decreases down group as valence electrons are further away from nucleus. Effect of increased radius is much greater than the increase in ENC decreasing element electronegativity. Electronegativity increases to top right of periodic table Fluorine most electronegative whilst francium is least

Answer 26

For trends concerning behaviour of valence electrons Across period, effect of zeff dominates has principle quantum number is unchanged Down group, effect of principle quantum no dominates over zeff

Answer 27

Greater difference in electronegativity of two bonding atoms, the more polar the bond is

Answer 28

>1.8: Large difference in electronegativity (Ionic Bond) 0.4-1.8: Moderate difference in electronegativity (Polar Covalent) <0.4 Small or no difference in electronegativity (Non-polar)

Answer 29

When atoms with large difference in electronegativity participate in bonding, electron transfer occurs leading to one atom becoming positive and the other negative When atoms have a moderate difference, electrons are shared unequally drawing electrons closer to the atom with higher electronegativity. Leads to formation of electric dipole where more electronegative element is slightly negative and the other positive. When atoms have a small difference, electrons are shared equally and no polarity develops

Answer 30

In ionic compounds, all atoms have full valence electrons achieved through transfer of valence electrons from one species to another

Answer 31

In covalent compounds, all atoms similarly have a full valence shel of electrons which is attained through sharing valence shell electrons between two atoms.

Answer 32

Ionic compounds are defined by empirical formulas whilst covalent compounds are defined by their molecular formula. This specifies the actual no of atoms present in a molecule in a molecule of the compound.

Answer 33

The electrostatic attraction between positively and negatively charged components which arises due to transfer of electrons The bonds between atoms as pairs of electrons shared between atoms.

Answer 34

Exist as lattice structures Covalent compounds exist in a variety of different shapes

Answer 35

Only valence electrons (typically s and p orbital electrons) are involved in determining molecular shape. Main idea is that the structure around the given atom is determined by minimising electron pair repulsion. Bonding groups and lone pairs around given atom should be as far away as possible.

Answer 36

Atoms in species are held together by pairs of electrons (bonding pairs) Some atoms within species may have pairs of electrons that are not involved in bonding (lone pairs) As electron pairs are negatively charged, they repel each other. On each atom, the electron pairs adopt positions as far away from one another as possible.

Answer 37

The electron group geometry is determined by all the electron groups in the molecule The molecular geometry is the shape governed by atoms in the molecule and is determined by the bonding groups

Answer 38

Linear Trigonal planar Bent Tetrahedral Trigonal pyramid Bent Trigonal Bipyramidal Octahedral

Answer 39

Ionic networks consist of cations and anions bonded by electrostatic attraction (positives and negatives attracted to each other)

Answer 40

Hard and brittle (when crystal is hammered, layers of ions slide over each other causing like ions to come into close proximity, repelling each other causing it to shatter) High mp and bp (strong ionic bonds must be broken to melt ionic network requiring lots of heat energy) Cannot conduct electricity in solid state Can conduct in molten or aqueous state (as the ions are liberated from lattice and are free to conduct electricity)

Answer 41

Covalent network are formed by extensive networks or chains of atoms bonded together by strong covalent bonds

Answer 42

No molecules as it is a continuous crystal such as diamon, sand (silicon dioxide) and graphite Are hard (presence of very strong covalent bonds throughout lattice) Are brittle (covalent bonds are directional and will break) High mp and bp (Strong covalent bonds must be broken to melt covalent network which requires lots of heat energy) Most don't conduct electricity Don't dissolve in water and don't melt rather decomposing at high temperatures Hence, most covalent networks don't conduct electricity Graphite is exception

Answer 43

Metals are composed of 3D lattice of metal cations embedded in a sea of delocalised valence electrons

Answer 44

Cations are arranged in a regular 3D lattice whilst valence electrons freely occupy space around them, offering multi-directional metallic bonding. This provides a strong cohesive force that holds the metals cations together. Metals are hard but softer than covalent networks or ionic networks Metals are malleable (can be hammered into sheets) Metals are ductile (can be drawn into wires) When hammered, metal cation lattice structure is disturbed but delocalised valence electrons cushion this deformation since they provide multi-directional bonding High mp and bp (electrostatic interactions between valence electrons and metal cations must be broken which requires a lot of energy) Metals conduct electricity in solid or molten state Metals are lustrous (delocalised electrons reflect light)

Answer 45

Covalent molecular structures are composed of discrete covalent molecules with no chemical bonds between them. An example of this is ice.

Answer 46

Are held together not by chemical bonds but intermolecular forces/bonds Intermolecular forces/bonds are weaker than chemical bonds and act between molecules. Are distinct from intramolecular bonds which are covalent bonds Covalent molecular structures are soft (intermolecular bonds are weaker than ionic or covalent bonds) Have low mp and bp (weaker intermolecular bonds between molecules need to be broken to melt constant molecular structure which doesn't need a lot of energy. Don't conduct electricity

Answer 47

Allotropes are different structural forms of the same element in the same state. They exhibit different physical properties

Answer 48

Diamond, buckminsterfullerene, graphite

Answer 49

Has covalent network structure Hard Every carbon atom is bonded to its neighbours by four strong covalent bonds arranged in tetrahedral geometry. Doesn't conduct electricity High mp and bp (in order to melt or boil diamond, strong covalent bonds need to be broken which requires immense energy) Colourless, transparent and lustrous

Answer 50

Composed of layers of covalent networks Within each layer, each carbon atom is bonded to only three other carbons forming trigonal planar geometry This allows one valence electron per carbon atom to be delocalised between layers, creating weak interactions that hold the layers together Soft and slippery (layers are weakly held together consequently they can easily slip over one another Reasonable electrical conductor Very high mp and bp (strong covalent bonds need to be broken)

Answer 51

A spherical cage-like structure of carbon atoms with chemical formula of C60 Has covalent molecular structure Poor electrical conductor Low mp and bp Weak intermolecular forces need to be broken which don't require as much energy to break.

Answer 52

A covalent molecule is polar if it possesses a net dipole moment Is dependent on polarity of bonds and molecular geometry If there exists no cancellations, then the molecular is polar If none of the bonds or all the dipoles, cancel out, then it is non-polar

Answer 53

Occur between two polar molecules. Polar molecules have a net dipole. Molecules arrange themselves such as opposite charges attract each other. These electrostatic interaction are named dipole-dipole interactions Are considerably weaker than ionic or covalent bonds Strength depends on size of overall dipole moment. Elements with large electronegativity differences tend to have larger dipole moments Greater dipole moment, stronger the dipole-dipole interactions

Answer 54

Special type of strong dipole-dipole interactions Only occurs when hydrogen is directly bonded to highly electronegative elements: F, O or N (Large difference in electronegativity results in a greater bond polarity. Small size of H atom allows the close approach of these dipoles) H-bonding is much stronger than dipole-dipole interactions but weaker than ionic or covalent bonds

Answer 55

They exist between any molecules regardless of polarity This is the primary intermolecular force that exists within non-polar molecules Strength of dispersion forces increases with molecular mass that is larger molecules have larger dispersion forces than smaller molecules Larger molecules have greater no of electrons and have increased chance of forming momentary dipoles Are weaker than dipole-dipole and h-bonding.

Answer 56

Since electrons move around randomly, a momentary non-uniform distribution of charge causes the formation of a temporary dipole The instantaneous dipole that forms in one atom/molecule can then affect electron distribution in neighbouring atom/molecule and induce similar dipole Leads to an intermolecular attraction that is relatively weak and short lived aka dispersion force

Answer 57

Intermolecular forces are broken, the stronger the intermolecular forces, the more energy required to break them thus having a higher mp and bp

Answer 58

Bonds between atoms within molecule or compound Examples include covalent, ionic or metallic. Are strong When boiled, covalent networks, ionic networks and metals are overcome

Answer 59

Bonds/forces between molecules Examples include H-bonding>dipole-dipole>dispersion forces Are weak Covalent molecules are overcome when boiled

Answer 60

The extent to which the findings of repeated experiments, conducted under identical or similar conditions, are consistent with each other. The extent to which a measured value agrees with its true value Validity refers to whether all the variables within an experiment, apart from the independent and dependent, were controlled.

Answer 61

On graph, independent lies on x axis and dependent lies on y axis Independent variable must be either first column or row and the dependent variable can go in the rest of the column or rows.

Answer 62

Error: Measured value - true value Error percent: |(Measured value - true value)|/true value x 100