Question

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 Sodium 9. Describe the relationship of the three elements in Model 2 with regards to their relative positions on the periodic table. 10. Draw a cirde and lightly shade the area representing the core of each atom in Model 2. Potassium 11. Refer to a periodic table to complete the table in Model 2. Advanced Periodic Trends

can someone help me to answer those questions

Answer 1

8)

Effective Nuclear Charge are the attractive positive charge of nuclear protons acting on valence electrons.The effective nuclear charge is always less than total number of protons present in a nucleus due to shielding effect.

From our understandings of Effective Nuclear Charge, let us explain each of the terms.

a) Atomic radius - In a periodic table, atomic radii decreases from left to right across a row due to difference in effective nuclear charges. As we go from left to right across the row, the nuclear charge increase from +3 to +10 and also the electrons in same principal shell are not very effective at shielding one another from nuclear charge. Thus as we proceed across the row the increasing nuclear charge is not effectively neutralized by the electrons being added to the 2s and 2p orbitals. Hence the result is a steady increase in effective nuclear charge and steady decrease in atomic size.

b) Ionization energy - It is the energy required to remove the most loosely held electron from a gaseous atom or ion. In a periodic table, on moving across a row, the effective nuclear charge increases and due to this the outermost electron will be pulled stronger by the nucleus and it will require more energy to take out that electron and hence the ionization energy increases from left to right across a row.

c) Electronegativity - It is the property of an atom which increases with its tendency to attract the electron of a bond. More electronegative elements holds the bond electrons closer to themselves. So the electronegativity increases across a row with increase in effective nuclear charge since both are directly proportional.

9)  

Lithium, sodium, and potassium are all part of a group called the alkali metals. They are all found in group 1 of the periodic table. They are all located in the first vertical line on the left side of the periodic table. They are all soft metals in elemental form and they all react violently with water. They react so strongly because they all readily lose an electron to form the +1 cation very easily. This is because they only contain one electron in their valence shells so it is easily removed to achieve a stable octet of electrons in the outermost energy shell. All three elements are having same color which is silver. The melting point and boiling [point decreases from lithium to potassium whereas atomic weight increases from lithium to potassium. The ionization energy and electronegativity also decreases from top to bottom.

Question number 10 has already been solved in the question paper.

11) The table in model-2 are filled in the picture given below.

[ 610 Atomic Number 3 charee Lithium sodium Potassium

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