# Chem assignments

version from 2017-12-10 21:35

## Assgn 8

What is meant by the term effective nuclear chargethe attractive positive charge of nuclear protons acting on valence electrons
How does the effective nuclear charge experienced by the valence electrons of an atom vary going from left to right across a period of the periodic tableGoing from left to right across a period, nuclear charge increases while the number of electrons in the core is constant. This results in a increase in Zeff
Which will experience the greater effective nuclear charge, the electrons in the n=3 shell in Ar or the n=3 shell in Kr, which one will be closer to the nucleusFor Ar, you have 1s2 2s2 2p6 3s2 3p6 with 8 valence electrons (n=3) and 10 non valence electrons (shielding). Zeff = 18- 10 = +8. The n=3 shell electrons in Kr are the same as for Ar but Kr has 36 protons whereas Ar has only 18 protons. So, the Zeff would be greater for n=3 electrons in Krypton. 36 - 10 = 16 compared to 8 as Zeff. The Kr electrons will be closer. There are10 electrons being polled by 18 protons in Ar but there are 10 electrons being pulled by 36 protons in Kr bringing them closer to the nucleus
We estimate the effective nuclear charge Zeff byZ-S, where Z is the atomic number and S is the number of electrons 'between' the electrons of interest (here the n=3 electrons) and the nucleus. For this problem, S =10, so
he increase in atomic radius when moving down a group (column) is more significant thanthe increase in atomic radius when moving left across a period (row)
T or F; Anions are larger than their corresponding neutral atomsT
As Z stays constant and the number of electrons increases, the electron-electron repulsions ___, and the anion becomes largerincrease
The reverse is true for the cation, which becomes _________ than the neutral atomsmaller
For cations with the same charge, ionic radii _________ going down a column, because there is an _________ in the principle quantum number and the average distance from the nucleus of the outer electronsincrease, increase
removing one electron to form Fe3+ significantly ___ repulsion, increasing the nuclear charge experienced by each of the other d electrons and decreasing the size of the ionreduces
chap 7 flashcardshttps://quizlet.com/56836417/chemistry-chap-7-flash-cards/
Which neutral atom is isoelectronic with each of the following ions: Ga3+, Zr4+, P3+, K+, Pb2+, I- these are easy actually - just go to periodic table and for example march to the left by three for Ga+3 to get Ni, march one to the right for I- to get Xe (mid you, method only works for non-transition metals). New way: P³⁺The atomic number of P is 15. P atom has 15 electrons, and thus P³⁺ ion has 15 - 3 = 12 electrons. Mg (magnesium) is the element with atomic number 12, and Mg atom has 12 electrons. Hence, Mg atom is isoelectronic with P³⁺ ion.
go overhttp://users.stlcc.edu/mhauser/hw7.pdf
Ionization simply means thatyou want to remove an electron from the atom
When you are talking about ionisation energies, everything must be present inthe gas state
Ionisation energies are measured in kJ mol-1 (kilojoules per mole)