Chapter 3- Periodicity Flashcards
Which sub orbital is being filled on the far left of the periodic table?
s-orbitals
Which sub orbital is being filled in the middle of the periodic table?
d-orbitals
Which sub orbital is being filled on the far right of the periodic table?
p-orbitals
What is the effective nuclear charge (ENC) determined by? (4 things)
- Distance from the nucleus to the outer-shell
+ largely depends by the # of shells - Shielding by inner electrons
+ inner-shells reduce the effect of the nucleus due to repulsion - Nuclear charge
+ greater the nuclear charge = the greater the attraction provided the # of shells and shielding = the same - Sub-shell and electron pairing
+ when trends can’t be explained by above things = look at diff in sub-shells/ by electron pairing orbitals
Atomic Radius
The dist. from the nucleus to the outer most electron
+ measured as half the dist. betw. 2 bonded atoms
Descending a group the atomic radius___? and why?
+ INCREASES
+ Cuz the outer electrons in “NEW energy level”
= further from the nucleus
+ the increase in nuclear charge, cancelled out by increase distance and shielding
Across a period the atomic radius___? and why?
+ DECREASES
+ Cuz the increase in “NUCLEAR CHARGE”
= as more protons r added while electrons = put in the same energy level
Ionic Radius
Dist. betw. nucleus and outermost electrons of positive metal CATIONS or negative non-metal ANIONS.
Descending a group the ionic radius___?
+ BOTH metal cations and non-metal anions = INCREASE in size
Descending a group metal cations get___? and why?
+ SMALLER than their atoms!
+ Cuz they lose their outer-shell electrons
+ there’s ALSO reduction in shielding = a greater attraction of outer electrons to the nucleus!
Descending a group non-metal anions get___? and why?
+ LARGER than their atoms!
+ Cuz they’ve gained electrons in their outer-shell
= increases the repulsion between electrons = size gets bigger!
Across a period the ionic radius___? and why?
+ REDUCTION in size
= due to the increase in protons (nuclear charge) whilst all the ions hv. the same electronic configuration.
Descending a group the ionisation energy___? and why?
+ DECREASES
+ outer shell electrons easier to remove = further and more shielding from the nucleus due to the increase in atomic radius as the atoms hv. more shells!
Across a period the ionisation energy___? and why?
+ generally INCREASES
+ cuz the increase in protons (nuclear charge) = increase attraction form outer-shell electrons which are in the same energy level.
Electronegativity
The ability of an atom to attract a pair of electron towards itself within a COVALENT bond.
Descending a group the Electronegativity ___? and why?
+ DECREASES
+ cuz the bonding electrons = further and more shielded from the nucleus due to an increase in the atomic radius as the atoms have more shell.
Across a period the Electronegativity ___? and why?
+ INCREASES
+ cuz the increase in # of protons (nuclear charge) = causes an increase in the attraction for the bonding electrons, which are in the SAME energy level.
Most electronegative elements?
FON
Electron Affinity
The energy change when ONE mole of electrons are ADDED to one mole of GASEOUS atoms.
First electron affinity is exo or endothermic? and why?
Exothermic
+ cuz energy is RELEASED when an electron bonds to an atom.
Descending a group the electron affinity___? and why?
Generally becomes LESS negative. = decease in energy released!
+ cuz the incoming electrons = further and more shielded from the nucleus due to the increase in atomic radius as the atom has more shells.
Across a period the electron affinity___? and why?
Generally become MORE negative = increase in energy released!
+ cuz the increase in the number of protons (nuclear charge) causing an increase in attraction for the extra electron.
Metals have LOW___ and ___?
Ionisation energies and electronegativities
Metals form compounds with non metals by by what type of bonding?
Ionic bonding = losing electrons to from + cations (pawsitive! >
Properties of metals (4)
- Solid at room temperature (except for mercury)
- High m.p and b.p
- Malleable and Ductile
- Good conductors of both heat and electrocity in solid state
Are the elctronegativites and ionisation energy in non-metals high or low?
HIGH!
What do the physical properties of non-metals depend on?
How the covalent bonds join atoms of the element.
If covalent bonds in non-metals give rise to molecules (small # of atoms joined) what state are they in?
+ Gas
+ Liquid
+ Low m.p solids
If covalent bonds produce a 3D network what state are they in?
High m.p solids
Do covalent structures conduct electricity?
No
Except for graphite (exception with regards to hardness and conductivity )
Metal oxides?
are BASIC
Metal oxides react w/ water to form?
Their hydroxides
Metal Oxides + Acid → ? + ?
Salt + Water
Is Aluminium basic or acidic?
Neither = It’s Amphoteric
→ Reacts and dissolves in both Acids and Bases
(displays properties of metallic and non-metallic oxides)
Silicon dioxide = though has little acid-base activity → does show some acidic properties by?
Slowly dissolving in hot conc. alkalis to form silicate.
Non-metal oxides?
are ACIDIC
What oxides contribute to acid rain?
Sulfur and nitrogen oxides
What effect does acid rain have on aquatic life?
Makes lake water too acidic for aquatic life to survive
How does acid rain damage plants?
+ Damage leaves and roots by causing enhance leaching of metal ions from soil
+ esp. Mg2+ = essential for chlorophyll production
If the metal ions that are leached from the soil enter water supplies what is the dangers?
+ Negative impact on human health
+ Al3+ linked to increased risk of Alzheimer’s disease
How does acid rain damage infrastructure?
+ Enhance corrosion of limestone
+ Increase the rate at which iron and steel rust because of the low pH
Why do elements in the same group of the periodic table have similar properties?
Same # of electrons in the outershell (valence shell)
Properties of Alkali metals (Li Na K Rb Cs)
+ Soft malleable metal and low m.p ( because each atom can ONLY contribute “1” electron to metallic bonding = less strong than for other metals)
+ low density = because they are the largest atoms in their period of p. table
Descending the group of Alkali metals what happens to the hardness and m.p?
+ Gets softer
+ m.p decreases
As the attraction betw/ nucleus and outer electrons decrease as a result of the increase in size of atoms
Alkali metals always form what numbered ions?
+1 ions (cuz only 1 electron in outershell)
Why do Alkali metals Tarnish rapidly?
Because they are chemically really reactive
+ They react w/ oxygen to form oxides on exposure to oxygen
In excess oxygen what happens to Alkali metals?
React further to produce oxides containing a higher proportion of oxygen
What compounds to Alkali metals create when reacted w/ Halogens?
Ionically bonded compounds
Alkali metals + water → ? + ?
Metal hydroxide + H (g)
VERY SPONTANEOUSLY
What do Halogens exist as?
Diatomic molecules (F2, Cl2 etc.)
Descending group what happens to physical state?
Gas (F and Cl) → Liquid (Br) → Solid (I = forms purple vapour when heater)
Why are halogens really electronegative?
Require just “1” electron to fill outershell
→ They react readily to gain electrons and form single charged ions
What happens to reactivity down a group?
Decreases
→ cuz ease at which they gain electrons decrease = cuz electrons gained are further away from nucleus = less strongly attracted
Are halogens soluble in water?
Slightly = cuz they’re non-polar
→ so only bond to polar water molecules by dispersion forces
What colour do:
+ Conc. solution of Cl
+ Conc. solution of Br give?
+ Green tinge
+ Darken from yellow → orange → brown as conc. increases
In non-polar solvents (s.a Hexane) what colour soln does Iodine form?
Violet
In polar solvents (s.a water/ ethanol) what colour soln does Iodine form?
Brown
In aqueous solution halogens react to form what solution?
Slightly acidic soln
w/ compound HOX (X halogen)
X2 + H2O → H+ (aq) + X- (aq) + HOX (aq)
What agent does HOX act as? and why?
Oxidising agent = cuz it can readily donate its Oxygen to other substances
What does Chloric acid (HOCl) do to coloured dyes?
Oxidize them to colourless products
Chloric (I) acid and conjugate base = Choride (I) ion (OCl-) can be useful because of what properties?
+ Used as bleaches (e.g for paper)
+ Used as disinfectant (e.g for pool)
Halogens act as what agents?
Oxidising agents as readily gains electrons
Descending the group what happens to the size of the atoms?
Increases = attraction betw/ nucleus and electrons become less → become LESS powerful oxidising agents
Higher halogens will do what to the lower halogens?
Displace it from its salt by removing a valence electron
Transition elements
Elements that have a partially filled d-subshell in the elements of in 1 of its common oxidation state
Properties of Transition elements (5)
1) Variety of oxidation states
2) ability to form complex ions
3) Catalytic activity
4) Magnetic properties
5) Form colored compounds
Why does the successive ionisation energies of transition metals not increase largely?
Cuz 3d and 4s electrons have similar energies
What do the oxidation states of transition metals depend on?
Redox environment
→ The presence of species that readily gain or lose electrons
Except for Sc = all transition metals have what oxidation state?
+2
→ Corresponds to loss of 4s electrons
