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Effective Nuclear Charge and Periodic Trends
Coulombs Law describes the interaction between two charges and varies by the magnitude of these charges and inversely with the distance between them. ? ∝ ?1?2/? For atoms, we’ll label the charges as the nuclear charge and electron charge. ? ∝ ?????????/?
As you go up in atomic number (Z), the number of protons in the
nucleus increases, making the charge on the nucleus increase, so
that in general. ???? = ? ∙ (+1)
However if we think only of the electrons in the outermost shells (valence electrons), they do not see the full strength of the nuclear charge because it is partially shielded (or canceled out if you prefer) by the core electrons. So we define something called effective charge.
????????? ?ℎ???? = # ?? ??????? − # ?? ???? ????????? ???? = ? − ????
In general, Zeff increases as you go across in the periodic table.
1. Fill out the following table to verify that effective charge increases as you go across a row.
2. For which element in the above table will the coulomb interaction between nucleus and valence electrons be the strongest? The weakest?
The second trend we need to consider with Coulomb’s Law is the distance between the charges. This is an inverse relationship (? ∝ 1 ? ) so the interaction gets weaker as you get further away.
3. In general, as you go down a column in the periodic table, will the interaction between the nucleus and valence electrons get stronger or weaker? Explain.
While you can simply memorize all the different periodic trends, many can be understood in terms of the two competing factors in Coulombs law ( ???? ??. ????????, r). Atomic radius – average distance between the nucleus and the outermost (valence) electrons.
4a. Going across rows in the periodic table, do you expect atomic radius to increase or decrease?
b. Going down columns in the periodic table, do you expect atomic radius to increase or decrease?
c. Put the following atoms in order from smallest to largest: Be, F, C, O
d. Put the following atoms in order from smallest to largest: Mg, Ba, Ca, B
Ionic radius – To understand ionic radii we must also consider the effect of electron-electron repulsion.
a. Cations have less electron-electron repulsion and are smaller than the corresponding neutral atom.
b. Anions have more electron-electron repulsion and are larger than the corresponding neutral atom.
5. When determining trends in ionic radius, we need to compare similar species. Similarities are:
a. Same number of electrons, different numbers of protons Which will be smaller, a species with 12 electrons and 10 protons, or one with 12 electrons and 12 protons?
b. Same number of protons, different number of electrons. Which will be smaller, a species with 12 electrons and 12 protons, or one with 10 electrons and 12 protons?
c. Same group of the periodic table, same ionic charge. State an example of this situation and specify which ion is larger.
Effective Nuclear Charge and Periodic Trends Coulombs Law describes the interaction between two charges and varies...
Use the concepts of effective nuclear charge, shielding, and value of the valence orbital to explain the trend in atomic radius as we move across a period in the periodic table. Match the words in the left column to the appropriate banks in the sentence on the right Reset Help bigger the sand increases As you move to the right across a row in the periodic table, the level stays the same However, the nuclear charge increases and the amount...
Part A Use the concepts of effective nuclear charge, shielding, and n value of the valence orbital to explain the trend in atomic radius as we move across a period in the periodic table. Match the words in the left column to the appropriate blanks in the sentence on the right Reset Help bigger the same Increases As you move to the right across a row in the periodic table, the n level increases. However, the nuclear charge decreases and...
Ionic Radii The size of ions as measured by ionic radii varies in a systematic manner. The size of the ion can be explained in part by effective nuclear charge, Zeff, which is the net nuclear charge felt by an electron. The effective nuclear charge takes into account the actual nuclear charge and the shielding of this charge by inner electrons. When an atom loses electrons, the resulting cation is smaller both because the remaining electrons experience a larger Zeff...
can someone help me to answer those questions 8. Explain the trend as you move across a row of the periodic table for each of the following some properties using your understanding of effective nuclear charge. Atomic radius b. Ionization energy 6. Electronegativity STOP Model 2 - The Alkali Metals Pare Atomic Number Core Charge Atomic Radius 1st lonization Energy Electro- negativity Lithium 0.91 Sodium 152 pm 186 pm 227 pm 520 kJ/mole 496 kJ/mole 419 kJ/mole 0.87 0.73 Potassium...
- Parta Explain why atomic radius decreases as you move to the right across a period for main-group elements but not for transition elements Match the words in the left column to the appropriate blanks in the sentences on the right Reset Help proton larger As you move to the right across a row in the periodic table for the main-group elements, the effective nudear charge (Zl) experienced by the electrons in the outermost principal energy level resulting in a...
Periodic Trends - Ionization Energy Name Chem Worksheet 6-4 Ionization describes the process in which an electron is removed from an atom in the gaseous state. The amount of energy required to remove the outer electron is called the first ionization energy. Successive electrons can be removed as well. The following equations show the first and second ionization for the nitrogen atom. First lonization N(g) -N')+ Second Ionization N (8) - N*)+e Bohr's model of sodium. The outer First lonization...
13) Which statement is true about effective nuclear charge? A) effective nuclear charge increases as you move to the right across a row in the periodic table and increases as you move down a column. B) effective nuclear charge increases as you move to the right across a row in the periodic table and decreases as you move down a column. c) effective nuclear charge decreases as you move to the right across a row in the periodic table and...
Question 4 (1 point) Do you predict 52- or Ca2+ to have a smaller ionic radius? Why? Ca2+ is smaller because it has only two valence electrons whereas S2- has six. OCa2+ is smaller because its nucleus has a larger positive charge which exerts a stronger force than the nucleus of S2- on the same number of electrons. Os2- is smaller because it contains fewer electrons than Ca2+ and therefore has a smaller electron cloud. OS2- is smaller because it...
Could you please give me answers for these ? thanks 1. Atomic radius decreases as we move from left to right in the periodic table. Which of the following is the BEST explanation for this trend? a. The electrons in the valence shell increase in number and thus interact more with one another as we move from left to right. b. There is more shielding of the inner electrons as we move from left to right. c. The electrons in...
Please answer these for me im totally confused001 10.0 pointsConsider the atomsA) nitrogen B) bismuth C) arsenicArrange them in order of increasing ﬁrstionization energy.1. A, C, B2. B, A, C3. C, B, A4. B, C, A5. A, B, C6. C, A, B002 10.0 pointsWhich of the following is a measure of thetendency of an atom in a molecule to attractelectrons to itself ?1. L nonbonding2. polar3. electronegativity4. ionization003 10.0 pointsWhich ion has the larger radius?1. Unable to determine2. Both have...