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KIMIA UNSUR



  NADHYA FADLILLAH
XII AKSELERASI - KIMIA
UNSUR – UNSUR LOGAM
        ALKALI
          dan
     ALKALI TANAH



Unsur logam alkali dan alkali tanah merupakan unsur-unsur logam
yang sangat reaktif, artinya bahwa unsur-unsur tersebut dapat
bereaksi dengan banyak unsur. Tapi, kereaktifitas logam alkali lebih
besar dibandingkan dengan logam alkali tanah
Konfigurasi Elektron
Alkali (IA)                Alkali Tanah (IIA)
• 3Li         : [He] 2s1   • 4Be           : [He] 2s2
• 11Na        : [Ne] 3s1   • 12Mg          : [Ne] 3s2
• 19K         : [Ar] 4s1   • 20Ca          : [Ar] 4s2
• 37Rb        : [Kr] 5s1   • 38Sr          : [Kr] 5s2
• 55Cs        : [Xe] 6s1   • 56Ba          : [Xe] 6s2
• 87Fr        : [Rn] 7s1   • 88Ra          : [Rn] 7s2
Kelimpahan Logam Alkali Di Alam




Na   : 2,8 %   Rb   : 0,0078 %   Cs : 0,0003%
K    : 2,6 %   Li   : 0,0007 %
Kelimpahan Logam Alkali Tanah Di Alam




Ca   : 3,4 %   Ba   : 0,04 %
Mg   : 1,9 %   Sr   : 0,03 %
Sifat Logam Alkali
        Logam alkali yaitu unsur-unsur golongan IA dalam sistem
periodik, merupakan logam yang paling reaktif (pembentuk basa kuat),
mudah melepaskan elektron valensinya (ns ¹) membentuk senyawa
dengan tingkat oksidasi +1.
        Senyawa-senyawa logam alkali umumnya tergolong senyawa
ion dan mudah larut dalam air. Maka tidak heran jika banyak
ditemukan di air laut, selain itu bersifat lunak seperti karet penghapus,
sehingga dapat diiris dengan pisau.
        Pada suhu ruang logam alkali mempunyai wujud padat (Li, Na,
K, Rb) dan cair (Cs, Fr)
Warna Nyala
Logam Na        Logam Rb




Logam Li        Logam Cs




Logam K
Sifat Logam Alkali Tanah
       Logam alkali tanah yaitu unsur-unsur golongan IIA,
kereaktifannya dibawah alkali, namun dengan 2 elektron valensi
(ns²) yang dimilikinya, logam alkali tanah pun mudah melepaskan
elektronnya membentuk senyawa dengan tingkat oksidasi +2.
       Semua logam alkali tanah pada suhu kamar berwujud
padat, berwarna putih perak, kecuali Berilium yang berwarna abu-
abu. Logam alkali tanah di alam terdapat dalam bentuk senyawa
yang tidak larut di dalam tanah.
Warna Nyala
• Logam Sr




• Logam Ba




• Logam Ca
Pembuatan
Dengan elektrolisis leburan
              garamnya.
              NaCl (l)        Na+ (l) + Cl- (l)
Katoda        Na+ (l) + e-  Na (s)
Anoda         Cl- (l)         1/2 Cl2 (g) + e-
---------------------------------------------------------
              Na+ (l) + Cl- (l)  Na (s) + 1/2 Cl2 (g)
Kegunaan
Kesadahan Air

Air Sadah ialah air yang sukar berbuih dengan sabun dan banyak
mengandung ion Ca2+ dan Mg2+. Air sadar bukan merupakan air yang
berbahaya, karena memang ion-ion tersebut dapat larut dalam air. Akan
tetapi dengan kadar Ca2+ yang tinggi akan menyebabkan air menjadi
keruh.
1. Kesadahan Sementara
Mengandung Ca(HCO3)2 dan Mg(HCO3)2
Dapat dihilangkan dengan pemanasan
Contoh : Ca(HCO3)2 (aq) ® CaCO3 + H2O (l) + CO2 (g)

2. Kesadahan Tetap
Mengandung CaSO4 dan MgSO4
Dapat dihilangkan dengan menambahkan soda ash (Na2CO3)
Contoh : MgSO4 (aq) + Na2CO3 (aq) ® MgCO3 + Na2SO4 (aq)
Kimia unsur golonga i dan ii a

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Kimia unsur golonga i dan ii a

  • 1. KIMIA UNSUR NADHYA FADLILLAH XII AKSELERASI - KIMIA
  • 2. UNSUR – UNSUR LOGAM ALKALI dan ALKALI TANAH Unsur logam alkali dan alkali tanah merupakan unsur-unsur logam yang sangat reaktif, artinya bahwa unsur-unsur tersebut dapat bereaksi dengan banyak unsur. Tapi, kereaktifitas logam alkali lebih besar dibandingkan dengan logam alkali tanah
  • 3. Konfigurasi Elektron Alkali (IA) Alkali Tanah (IIA) • 3Li : [He] 2s1 • 4Be : [He] 2s2 • 11Na : [Ne] 3s1 • 12Mg : [Ne] 3s2 • 19K : [Ar] 4s1 • 20Ca : [Ar] 4s2 • 37Rb : [Kr] 5s1 • 38Sr : [Kr] 5s2 • 55Cs : [Xe] 6s1 • 56Ba : [Xe] 6s2 • 87Fr : [Rn] 7s1 • 88Ra : [Rn] 7s2
  • 4. Kelimpahan Logam Alkali Di Alam Na : 2,8 % Rb : 0,0078 % Cs : 0,0003% K : 2,6 % Li : 0,0007 %
  • 5. Kelimpahan Logam Alkali Tanah Di Alam Ca : 3,4 % Ba : 0,04 % Mg : 1,9 % Sr : 0,03 %
  • 6. Sifat Logam Alkali Logam alkali yaitu unsur-unsur golongan IA dalam sistem periodik, merupakan logam yang paling reaktif (pembentuk basa kuat), mudah melepaskan elektron valensinya (ns ¹) membentuk senyawa dengan tingkat oksidasi +1. Senyawa-senyawa logam alkali umumnya tergolong senyawa ion dan mudah larut dalam air. Maka tidak heran jika banyak ditemukan di air laut, selain itu bersifat lunak seperti karet penghapus, sehingga dapat diiris dengan pisau. Pada suhu ruang logam alkali mempunyai wujud padat (Li, Na, K, Rb) dan cair (Cs, Fr)
  • 7. Warna Nyala Logam Na Logam Rb Logam Li Logam Cs Logam K
  • 8. Sifat Logam Alkali Tanah Logam alkali tanah yaitu unsur-unsur golongan IIA, kereaktifannya dibawah alkali, namun dengan 2 elektron valensi (ns²) yang dimilikinya, logam alkali tanah pun mudah melepaskan elektronnya membentuk senyawa dengan tingkat oksidasi +2. Semua logam alkali tanah pada suhu kamar berwujud padat, berwarna putih perak, kecuali Berilium yang berwarna abu- abu. Logam alkali tanah di alam terdapat dalam bentuk senyawa yang tidak larut di dalam tanah.
  • 9. Warna Nyala • Logam Sr • Logam Ba • Logam Ca
  • 11. Dengan elektrolisis leburan garamnya. NaCl (l)  Na+ (l) + Cl- (l) Katoda Na+ (l) + e-  Na (s) Anoda Cl- (l)  1/2 Cl2 (g) + e- --------------------------------------------------------- Na+ (l) + Cl- (l)  Na (s) + 1/2 Cl2 (g)
  • 13.
  • 14.
  • 15.
  • 16.
  • 17.
  • 18.
  • 19. Kesadahan Air Air Sadah ialah air yang sukar berbuih dengan sabun dan banyak mengandung ion Ca2+ dan Mg2+. Air sadar bukan merupakan air yang berbahaya, karena memang ion-ion tersebut dapat larut dalam air. Akan tetapi dengan kadar Ca2+ yang tinggi akan menyebabkan air menjadi keruh. 1. Kesadahan Sementara Mengandung Ca(HCO3)2 dan Mg(HCO3)2 Dapat dihilangkan dengan pemanasan Contoh : Ca(HCO3)2 (aq) ® CaCO3 + H2O (l) + CO2 (g) 2. Kesadahan Tetap Mengandung CaSO4 dan MgSO4 Dapat dihilangkan dengan menambahkan soda ash (Na2CO3) Contoh : MgSO4 (aq) + Na2CO3 (aq) ® MgCO3 + Na2SO4 (aq)