chemistry

1. Group 1 ElementsGroup 1 Elements

2. Group 1 elementsGroup 1 elements
 Lithium, LiLithium, Li
 Sodium, NaSodium, Na
 Potassium, KPotassium, K
 Rubidium, RbRubidium, Rb
 Caesium, CsCaesium, Cs
 Francium, FrFrancium, Fr
 Group 1Group 1
elements areelements are
known asknown as alkalialkali
metalmetal..

3. Physical PropertiesPhysical Properties
ElementElement ProtonProton
numbernumber
AtomicAtomic
radiusradius
(nm)(nm)
MPMP
(ºC)(ºC)
BPBP
(ºC)(ºC)
DensityDensity
(g cm(g cm-3-3
))
ElectronegativityElectronegativity
LiLi 33 0.150.15 181181 13471347 0.530.53 1.01.0
NaNa 1111 0.190.19 9898 886886 0.970.97 0.90.9
KK 1919 0.230.23 6464 774774 0.860.86 0.80.8
RbRb 3737 0.250.25 3939 688688 1.531.53 0.80.8
CsCs 5555 0.260.26 2828 678678 1.871.87 0.70.7

4. All alkali metals areAll alkali metals are
 grey solidsgrey solids withwith shiny silvery surfaceshiny silvery surface
when freshly cut.when freshly cut.
 softsoft solids & can be easily cut.solids & can be easily cut.
 havehave low densitieslow densities as compared toas compared to
heavy metals.heavy metals.
 goodgood conductors of heat & electricityconductors of heat & electricity..
 havehave low melting & boiling pointslow melting & boiling points asas
compared to heavy metals ( Cu : mpcompared to heavy metals ( Cu : mp
1083 ºC, bp 2567 ºC).1083 ºC, bp 2567 ºC).

5. Down the group,Down the group,
 Atomic radius ↑Atomic radius ↑
thethe number of shells occupied with e ↑.number of shells occupied with e ↑.
 Both mp & bpBoth mp & bp ↓↓
metallic bondingmetallic bonding between atomsbetween atoms
becomesbecomes weakerweaker,, less heat energyless heat energy
required to overcome the metallic bondingrequired to overcome the metallic bonding
during melting & boiling point.during melting & boiling point.
 density ↑density ↑
increase inincrease in atomic mass >atomic mass > increase inincrease in
volume.volume.
 alkali metals become softeralkali metals become softer

6. Chemical PropertiesChemical Properties
 Very reactiveVery reactive –– must be kept inmust be kept in paraffin oil.paraffin oil.
 Alkali metal + HAlkali metal + H22OO → metal hydroxide + H→ metal hydroxide + H22
2Na + 22Na + 2HH22OO → 2NaOH + H→ 2NaOH + H22
 Alkali metal + OAlkali metal + O22 → metal oxide→ metal oxide
4Na +4Na + OO22 → 2Na→ 2Na22OO
 Alkali metal + ClAlkali metal + Cl22 → metal chloride→ metal chloride
2Na + Cl2Na + Cl22 → 2NaCl→ 2NaCl

7.  LiLi burns slowly with aburns slowly with a redred flame.flame.
 NaNa burns rapidly & brightly with aburns rapidly & brightly with a
yellowyellow flame.flame.
 KK burns very rapidly & brightly with aburns very rapidly & brightly with a
lilaclilac flame.flame.

8. Reactivity of alkali metalsReactivity of alkali metals
 Increases down the group.Increases down the group.
LiLi NaNa KK RbRb Cs FrCs Fr
more reactivemore reactive
 Reactivity is measured by theReactivity is measured by the easeease ofof
its atomits atom to lose its single valenceto lose its single valence
electronelectron to achieveto achieve stable noble gasstable noble gas
electron arrangement (duplet / octet).electron arrangement (duplet / octet).

9.  LiLi → Li→ Li++
+ e+ e--
(2.1)(2.1) (2)(2)
 NaNa → Na→ Na++
+ e+ e--
(2.8.1)(2.8.1) (2.8)(2.8)
 KK → K→ K++
+ e+ e--
(2.8.8.1)(2.8.8.1) (2.8.8)(2.8.8)

10.  Atomic sizeAtomic size ↑↑ from Li to Fr.from Li to Fr.
 Single valence e becomesSingle valence e becomes furtherfurther
awayaway from nucleus.from nucleus.
 This cause the single valence e to beThis cause the single valence e to be
moremore weakly pulledweakly pulled by the nucleus.by the nucleus.
 Thus, the single valence e can beThus, the single valence e can be
released more easilyreleased more easily down the group.down the group.
 Reactivity of alkali metals ↑Reactivity of alkali metals ↑ down thedown the
group.group.

11. Electropositivity of alkali metalsElectropositivity of alkali metals
 ElectropositivityElectropositivity is theis the ability to lose eability to lose e
to form positive ion.to form positive ion.
 Electropositivity of alkali metalsElectropositivity of alkali metals ↑↑
down the groupdown the group..
 Strength as reducing agent ↑Strength as reducing agent ↑ downdown
the group.the group.

12. Safety precautionsSafety precautions
in handling G1 elementsin handling G1 elements
 Avoid handling with bare hands.Avoid handling with bare hands.
 Wear safety goggles & gloves duringWear safety goggles & gloves during
the experiment.the experiment.
 Li, Na & K must be kept inLi, Na & K must be kept in paraffin oilparaffin oil..
 Rb, Cs & Fr are stored inRb, Cs & Fr are stored in sealedsealed
glass tubesglass tubes to prevent reacting withto prevent reacting with
oxygen & vapor in the air.oxygen & vapor in the air.

13. Stopping halfway is, in truth,Stopping halfway is, in truth,
more difficult & tiring thanmore difficult & tiring than
persevering on the path towardpersevering on the path toward
the final goal.the final goal.
~ Still Thoughts~ Still Thoughts