Chapter 3 - Periodic Properties of Elements Flashcards
Who summarised the elements by periodic law effectively creating the modern day periodic table?
Dmitri Mendeleev
How are elements listed in periodic table?
by increasing atomic number
What are rows on the periodic table called?
periods
What do all elements in a period have?
same number of shells
What are columns on the periodic table called?
groups - have similar properties
What do the sides of the periodic table largely consist of?
left = metals, right = non-metals
What is electron configuration?
the use of the 4 quantum numbers to account for all electrons in an atom and designate which orbitals they occupy
What is the Pauli exclusion principle?
no 2 electrons in an atom can have the same 4 quantum numbers
What are orbitals in the same principal energy level in hydrogen?
degenerate (have the same energy)
In multi electron atoms what are subshells?
not degenerate (energy depends on l)
What is Coulomb’s law?
energy of charged particles depends on their charges and separation
What is shielding?
electron repulsion in lower orbitals that screen outer electrons from nucleus
effective nuclear charge Zeffective = Z (actual charge) - S (no. of electrons shielding)
What is penetration?
outer electron moves into region occupied by inner electrons
What is the Aufbau principle?
a guide for determining the filling order of orbitals
What are the 3 rules of the Aufbau principle?
lower-energy orbitals fill before higher energy orbitals
an orbital can only hold 2 electrons which must have opposite spins (Pauli exclusion principle)
If two or more degenerate orbitals are available follow Hund’s rule
What is Hund’s rule?
if 2 or more orbitals with the same energy are available, one electron goes into each until all are half full
What are core electrons?
electrons in lower-energy shells
What are valance electrons?
electrons in all the sublevels with the highest principle energy shell
What is the significance of valance electrons?
one of the most important factors in how an atom behaves both chemically and physically - periodic table is designed to quickly identify valance electrons
what are the s block elements?
groups 1 and 2
what are the p block elements?
groups 3 to 8
What are the d block elements?
columns 3 to 12
What are the f block elements?
lanthanides and actinides
What are the 2 exceptions with electron configuration?
Chromium and Copper
What is the electron configuration of Chromium?
[Ar] 4s^1 3d^5
What is the electron configuration of Copper?
[Ar] 4s^1 3d^10
What are noble gasses?
group 8 (8 valance electrons apart from Helium with 2) especially non reactive due to filled outer shells
What are group 1 elements called?
Alkali metals
What are group 2 elements called?
Alkali Earth metals
What are group 7 elements called?
Halogens
If losing or gaining electrons are they likely to fill up highest orbital d first or the highest s orbital?
highest orbital d will fill first, so will lose electrons from s orbital first
What does Paramagnetic mean?
contains unpaired electrons
attracted to magnetic field
WHat does Diamagnetic mean?
contains paired electrons
not attracted to magnetic field
What trends do atomic size follow?
down group = radius increases
across period (right) = radius decreases
Why do as moving down a group the radius increase?
valence electrons occupy occupy larger orbitals and therefore the atomic size increases
Why do as moving across a period (right) why does radius size decrease?
both the nuclear charge and the number of electrons increases
core electrons shield outer electrons but outer electrons don’t shield one another
atomic size decreases across (right) the row because the effective nuclear charge increases
What are cations?
when an atom has lost electrons
What is the comparison between neutral atoms and cations?
cations atomic radius is smaller than corresponding neutral atoms
What are anions?
when an atom has gained electrons
WHat is the comparison between neutral atoms and anions?
adding electrons increases the size of the of the atom, much larger than corresponding neutral atoms
What is Ionisation energy?
the amount of energy required to remove an electron from an isolated neutral atom in the gaseous state
What happens to ionisation energy as you go down a column?
it decreases as valence electrons are farther away from nucleus, so electrons less shielded by nucleus
As you move across a row (right) what happens to Ionisation Energy?
increases ionisation energy as increased attraction of electrons
What are some of the exceptions to the ionisation energy laws?
Boron has a lower Ionisation energy than Beryllium due to a smaller Zeff (2p orbital penetrates less into 1s orbital) (as 2p found further from nucleus)
Oxygen and Nitrogen
Sulfur and Phosphorous (etc.)
(oxygen has a paired electron in the p orbital and with only 1 electron, there is an energy penalty for a paired electron so decreases ionisation energy
What is Electron affinity?
energy change when an atom in the gaseous state gains an electron
What are the trends of electron affinity?
moving down a column, electron affinity decreases (electron farther from the nucleus) - this only applies for alkali metals
moving across a row (from left to right) - electron affinity increases
What is an exception to trends of electron affinity?
Nitrogen - less favourable affinity than neighbours - 1s and 2s orbitals full 2p orbitals all half full
What are the properties of metals?
malleable and ductile
shiny, lustrous, reflect light
conduct heat and electricity
most oxides basic and ionic
form cations in solution
lose electrons in reactions - oxidised
How does metallic character trend on the periodic table?
increases as we go down
increases going from right to left
What are the properties of non metals?
brittle in solid state
dull, non reflective, solid surface
electrical and thermal insulators
most oxides acidic and molecular
form anions and polyatomic anions
gain electrons in reactions - reduced
