posted by .

Why is magnesium atom smaller than atoms of both sodium and calcium?

The location of the outer electrons for Mg are in closer to the nucleus than of Sodium or Calcium.

To add to the correct answer from Bob Pursley, consider the electronic configurations.
11Na = 1s2, 2s2, 2p6, 3s1
12Mg = 1s2, 2s2, 2p6, 3s2
20Ca = 1s2, 2s2, 2p6, 3s2, 3p6, 4s2

The outer electron for Na "sees" a charge of +1 (11 protons in the nucleus shielded by 10 electrons from the inner shells) whereas the outer electrons for Mg "see" a +2 charge (12 protons in the nucleus shielded by 10 electrons from the inner shells). Thus the Mg electrons are drawn in further due to the increased charge.
For Ca, the outer electrons see a +2 charge, the same as Mg, (20 protons in the nucleus shielded by 18 electrons from the inner shells) BUT the outer electrons are further out(in the 4s shell instead of the 3s) and the attraction falls off because of the distance.


Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. chemistry

    Water softeners often replace calcium ions in hard water with sodium ions. Since sodium compounds are soluble, the presence of sodium ions in water does not cause the white, scaly residues caused by calcium ions. However, calcium is …
  2. chemistry

    A precipitate of calcium phosphate is formed when aqueous solutions of sodium phosphate and excess calcium chloride are mixed. If 100.0 mL of 1.5 M sodium phosphate solution is the limiting reactant, how many grams of calcium phosphate …
  3. Chemistry

    If a solution of sodium phosphate, Na3PO4, is poured into seawater, precipitates of calcium phosphate and magnesium phosphate are formed. (Magnesium and calcium ions are among the principle ions found in seawater.) Write net ionic …
  4. Chemistry

    A solution of 100.00mL of 0.2000mol/L sodium carbonate and 200.00mL of 0.1000mol/L calcium nitrate solutions are mixed together according to the reaction: sodium carbonate + calcium nitrate→ calcium carbonate + sodium nitrate. …
  5. Chemistry

    I have to sort compounds into groups, separating them by if they are acidic, Ionic, or Covalent. Heres the list: Calcium Carbonate Sodium Hypochlorite Sodium Chloride Sodium Hydrogen Carbonate Acetic Acid Ammonium Hydroxide Silicon …
  6. chemistry

    A sodium atom when excited gives off two very specific wavelengths of visible light. What does this tell us about sodium?
  7. Chemistry

    1.How much energy is emitted by 1 mol of sodium ions emitting light at this wavelength?
  8. Science--HELP!!

    Can you please check my answers: 1. Dalton's idea that atoms cannot be divided into smaller parts was disproved by the discovery of _________ (electrons?
  9. Stoichiometry

    Suppose you wanted to add just enough 0.40M calcium chloride solution to 75.0mL of 0.60M of sodium carbonate solution for all of the sodium carbonate and calcium chloride to react. B) what mass of calcium carbonate would be produced …
  10. Chemistry

    Calcium Chloride reacts with sodium carbonate (aq) to form solid calcium carbonate and aqueous sodium chloride. Determine the volume of a 2.00M Calcium chloride solution that would be needed to exactly react with 0.0750L of 1.00M sodium …

More Similar Questions