Periodic Properties Flashcards
What are valence electrons in terms of principal energy levels?
In main groups the VE are electrons in the outmost principal energy
level
In transition elements the VE are electrons in the outermost principal energy levels and the outermost d electrons
What are core electrons in terms of principal energy levels?
complete principal energy levels and those in complete d and f sub-levels
Where are the orbital blocks in the periodic table?
s block is groups 1+2 including helium
p block is groups 13-18 not including helium
d block is groups 3-12
f block is where the table splits
What is different about chromium and copper’s electron configurations?
only put one electron in 4s orbital
4s^1 instead of 4s^2
What groups lost/gain electrons to become stable ions?
Group 1 and 2 will lose 1 or 2 electrons to get a configuration like noble gas, aluminum loses 3 to become like noble gas
group 16 and 17 will gain 1 or 2 electrons to become like noble gas
What is the trend for atomic size?
increases as you go down a column and decreases as you move from left to right across a row
Why does atomic size increase as you go down a column?
the highest principal quantum number increases (n), valence electron occupy larger orbitals therefore larger atoms
Why does atomic size decrease as you move across a row from left to right?
nuclear charge and the number of electrons increases but the value of n stays the same (larger Zeff)
What is effective nuclear charge? What is the formula?
actual amount of attraction between nuclues and electrons
Zeff=z-s
(z is atomic number) (s is number of shielding electrons)
What does a greater effective nuclear charge mean?
smaller atom size
What is true about the atomic radius of transition metals?
The first two rows follow the same trend as the rest of the elements
stays roughly the same because the number of electrons in the outermost value of n stays the same so the increase in nuclear charge is balanced by an increased number of screening electrons
What is the size of cations in relation to their normal atoms? Why?
they are much smaller than their corresponding atoms
because by decreasing the number of electrons while keeping the nuclear charge the same the attraction between the electrons and the nucleus increases, decreasing the size
What is the size of anions in relation to their normal atoms? Why?
they are much larger than their corresponding atoms
because by increasing the number of electrons while keeping the nuclear charge the same the attraction between the electrons and the nucleus decreases, increasing the size
What are isoelectronic species? What is affect on size?
All have the same number of electrons but different number of protons
At a fixed amount of electrons a greater nuclear charge results in a smaller atom or ion
What is ionization energy?
Energy required to remove an electron from an atom or ion in the gaseous state
What is relation between ionization energy and atomic radii? Why?
IE decreases as size increases
Further away means it needs less energy to remove (further away means lower IE)
What is the difference between first and second ionization energies?
Energy required to remove first electron vs energy required to remove the second electron
IE2»>IE1
What is the trends for first ionization energy?
Decreases going down a column because electrons are further away and held less tightly
Increases from left to right across a row because Zeff increases and therefore electrons are held tighter
What are some exceptions to the trends in IE1?
Beryllium has a greater IE than Boron
- Because the ve in boron is in 2p and ve in beryllium is in 2s
- 2p had a higher energy than 2s so it’s easier to remove (s orbital penetrates)
Nitrogen has a higher IE than oxygen
- because the repulsion between the paired electrons in oxygens 2p orbital make it easier to remove them
What is the trend for ionization energy for transition metals? Why?
IE increases across a row from left to right but the increase is smaller than main group elements
Third row has a higher IR than the first two rows
Charge of the nucleus increases
between rows but there is only a small increase in atomic size
What is electron affinity?
energy released when an electron is added to a neutral atom in the gas phase
What is the trend for electron affinity?
generally EA increases as we move from left to right across a row (not a strong trend)
What is an exception in the trend for electron affinity? Why?
Group 15 has a smaller electron affinity than group 14
Group 15 has a valence shell ns^2np^3, when an electron is added the repulsion makes the EA to be smaller than group 14
What are some properties of metals?
- good conductors of heat and electricity
- malleable and ductile
- high melting point
- tend to lose electrons
