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ChemistryPeriodic Properties
The correct order of increasing metallic character of Na, Be, P, Mg and Si is :
Options
1
P < Si < Be < Mg < Na
2
Be < Si < P < Mg < Na
3
P < Si < Na < Mg < Be
4
P < Mg < Be < Si < Na
Correct Answer
Option 1 : P < Si < Be < Mg < Na
Solution
1

Metallic character = tendency to lose electrons. Increases: down a group, left to right decreases in a period.

2

Period 3 elements (Na, Mg, Si, P):
Na (Group 1) > Mg (Group 2) > Si (Group 14) > P (Group 15)
Metallic character decreases left to right.

3

Be (Group 2, Period 2) vs Mg (Group 2, Period 3):
Mg is below Be in same group → Mg has MORE metallic character than Be.

4

Final order (increasing metallic character):
P < Si < Be < Mg < Na ✅

Metallic character: P < Si < Be < Mg < Na
Non-metals least → metals most
Theory: Periodic Properties
1. Metallic Character Definition

Metallic character = ease of losing electrons = tendency to form cations. High metallic character: low IE, low electronegativity. Trends: decreases left to right in period (increasing Z → harder to lose electrons). Increases down a group (larger atom → outer electrons farther → easier to lose). Most metallic: Cs, Fr (bottom-left of periodic table). Least metallic: F, O, N (top-right).

2. Comparing Elements Across Periods and Groups

Within Period 3: Na(Group 1) > Mg(Group 2) > Al(Group 13) > Si(Group 14) > P(Group 15) > S(Group 16) > Cl(Group 17). Na most metallic (IE₁=496 kJ/mol), P and Si are metalloid/non-metallic. Comparing Period 2 vs Period 3 in same group: Period 3 > Period 2 always (Mg > Be, Na > Li, Al > B). So Be < Mg.

3. Metalloids

Si and Ge are metalloids (semiconductors). B, Si, Ge, As, Sb, Te are usually classified as metalloids. Si: metallic lustre but brittle semiconductor. Si has some metallic properties but less than Be. So Si < Be in metallic character.

4. Electronegativity and Metallic Character Relationship

Metallic character ∝ 1/electronegativity. P(EN=2.19) > Si(EN=1.90) > Be(EN=1.57) > Mg(EN=1.31) > Na(EN=0.93). Higher electronegativity → less metallic character. This gives the same order as the answer: P < Si < Be < Mg < Na (increasing metallic character).

5. Reactivity Series vs Metallic Character

Reactivity series: Li > K > Ba > Ca > Na > Mg > Al > Zn > Fe > Ni > Sn > Pb > H > Cu > Hg > Ag > Pt > Au. This reflects reactivity with water/acid, not pure metallic character. Metallic character (from periodic trends) correlates but isn't identical. Li is MORE reactive than Na but has slightly less metallic character (smaller, higher IE). The reactivity series is kinetic; metallic character is thermodynamic.

6. Amphoteric Nature of Some Elements

Be and Al show amphoteric character (react with both acid and base): Be + 2HCl → BeCl₂ + H₂; Be + 2NaOH → Na₂BeO₂ + H₂. Al + 3HCl → AlCl₃ + 3/2H₂; 2Al + 2NaOH + 2H₂O → 2NaAlO₂ + 3H₂. This amphoteric nature shows Be and Al are on the borderline of metallic/non-metallic character. Na and Mg do NOT react with NaOH.

7. Flame Test Colours

Characteristic flame test colours (due to electronic transitions): Na: bright yellow (589nm, D-line). K: lilac/violet. Li: crimson red. Ca: brick red. Sr: carmine red. Ba: apple green. Cu: blue-green. Rb: red-violet. Cs: blue. These are used to identify metals in qualitative analysis. Na yellow is so intense it can mask other colours — use cobalt blue glass to filter yellow when testing for K.

8. Properties of Sodium and Magnesium

Na: soft metal, low melting point (98°C), very reactive with water (Na + H₂O → NaOH + ½H₂), stored in kerosene. Mg: harder than Na, mp=650°C, burns in CO₂ (not safe to use CO₂ extinguisher on Mg fire), reacts with hot water but slowly, burns with intense white light. Mg ribbon used in photography (flash). Both are s-block elements.

Frequently Asked Questions
1. Why is Be < Mg in metallic character? ⌄
Both Be and Mg are in Group 2 (alkaline earth metals). Going down a group, atomic size increases → outer electrons farther from nucleus → easier to remove → more metallic. Be (Period 2): smaller, higher IE₁(900 kJ/mol). Mg (Period 3): larger, lower IE₁(738 kJ/mol). So Mg loses electrons more easily → more metallic than Be.
2. Why is Si more metallic than P? ⌄
Both Si and P are in Period 3. Si(Group 14) is to the LEFT of P(Group 15) in the same period. Moving right in a period → nuclear charge increases → harder to lose electrons → less metallic. Si(EN=1.90) < P(EN=2.19) in electronegativity. Si is a metalloid (semiconductor); P is a typical non-metal. So Si has more metallic character than P.
3. Why is Na the most metallic in this group? ⌄
Na: Group 1, Period 3. IE₁=496 kJ/mol (lowest in the group). Loses 1 electron very easily. EN=0.93 (lowest in the group). Reacts vigorously with water and air. In this set (Na, Be, Mg, Si, P), Na has the highest metallic character because it's the most electropositive, lowest IE, leftmost in its period.
4. What is metallic character in terms of bond type? ⌄
High metallic character → forms ionic compounds (M → Mⁿ⁺ + ne⁻). Low metallic character → forms covalent compounds. Na forms NaCl (ionic). Mg forms MgCl₂ (ionic). Si forms SiCl₄ (covalent). P forms PCl₃, PCl₅ (covalent). P → purely non-metallic. This again confirms P < Si < Be < Mg < Na in metallic character.
5. How does metallic character relate to oxides? ⌄
Metallic oxides = basic (Na₂O, MgO, CaO dissolve in water to give bases). Non-metallic oxides = acidic (CO₂, SO₃, P₂O₅, NO₂ dissolve in water to give acids). Amphoteric oxides: BeO, Al₂O₃, ZnO, SnO (react with both acid and base). Order of oxide basicity: Na₂O > MgO > BeO(amphoteric) > SiO₂(acidic) > P₄O₁₀(acidic). Same trend as metallic character.
6. What about the metallic character of Li vs Na? ⌄
Li(Period 2, Group 1) vs Na(Period 3, Group 1): Na has more metallic character (lower IE, more reactive with water). But in terms of reactivity in organic/organometallic chemistry, Li is often MORE reactive due to polarising power. Na + H₂O is more vigorous than Li + H₂O, so Na appears more reactive. But Li reacts with N₂ directly (Li₃N), Na barely does — showing Li has unique chemistry. Generally: metallic character Li < Na < K < Rb < Cs down Group 1.
7. What are s-block elements? ⌄
s-block = Group 1 (alkali metals: Li, Na, K, Rb, Cs, Fr) + Group 2 (alkaline earth metals: Be, Mg, Ca, Sr, Ba, Ra). Their valence electrons are in s-orbitals. All are metals except Be and Mg which have some non-metallic/amphoteric character. H is sometimes placed in Group 1 but is a non-metal. All s-block elements have metallic character, but Group 1 > Group 2 in same period.
8. Complete order of metallic character across Period 3? ⌄
Na > Mg > Al > Si > P > S > Cl > Ar. Na: most metallic (IE₁=496). Mg(738) < Na. Al(577) — interesting anomaly (IE₁ Al < Mg due to 3p vs 3s). But metallic character: Mg > Al (Mg gives Mg²⁺, Al is borderline). Si: metalloid. P,S,Cl: non-metals. Ar: noble gas (no metallic character). Full increasing order: Ar < Cl < S < P < Si < Al < Mg < Na.
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