CHAPTER 4:

JOM KIMIA A1

PERIODIC TABLE OF ELEMENTS

C. GROUP 1 ELEMENTS

http://periodictable.com/

1. The elements in Group 1 are Lithium

2.1

Sodium

2.8.1

Potassium2.8.8.1

Rubidium

2.8.18.8.1

Caesium

2.8.18.18.8.1

Francium

2.8.18.32.18.8.12. They are also known as alkali metals which react with water to form alkaline solutions.3. All Group 1 elements have one valence electron in their outermost occupied shells.Physical Properties of Group 1 Elements1. Group 1 elements are soft metals with low densities and low melting points as compared to other metals such as iron and copper.

2. They have silvery and shiny surfaces.3. They are good conductor of heat and electricity.Elements/ symbolElectron arrangementAtomic radius (nm)Melting points (C)Boiling points (C)Density

(g cm-3)

Lithium, Li 2.10.1518013360.57

Sodium, Na2.8.10.19988830.97

Potassium, K2.8.8.10.23647560.86

Rubidium, Rb2.8.18.8.10.25397011.53

Table 1: Physical Properties of Group 1 Elements4. From Table 1, when going down the group, atomic size and density increase.5. When going down the group, melting points and boiling points decreaseChemical Properties of Group 1 ElementsLithium, sodium and potassium have similar chemical properties but differ in reactivity.

Let us carry out this Experiment! PracticalBook Experiment 4.1, page 35

Activity 4.3, page 38

1. Alkali metals react vigorously with water to produce alkaline metal hydroxide solutions and hydrogen gas. [Video]

Chemical equation; 2Li+ 2H2O 2LiOH + H2 Lithium Water

Lithium Hydrogen hydroxide gas

2Na+ 2H2O 2NaOH + H2

Sodium Water

Sodium Hydrogen

hydroxide gas

2K + 2H2O 2KOH + H2

Potassium Water Potassium Hydrogen

hydroxide gas

2. Alkali metals react rapidly with oxygen gas, to produce white solid metal oxides. Chemical equations; 4Li + O2 2Li2O Lithium Oxygen Lithium gas oxide 4Na+ O2 2Na2O

Sodium Oxygen Sodium

gas oxide

4K + O2 2K2O

Potassium Oxygen Potassium

gas oxide

3. Alkali metals burn in chlorine gas to form white solid metal chlorides. Chemical reaction; 2Li + Cl2

2LiCl

Lithium Chlorine Lithium

gas chloride

2Na + Cl2 2NaCl Sodium Chlorine Sodium gas chloride 2K + Cl2 2KCl Potassium Chlorine Lithium gas chloride 4. Alkali metals burn in bromine gas to form metal bromides. For example, 2Li + Br2

2LiBrLithium Bromine Lithium gas bromide2Na + Br2

2NaBr

Sodium Bromine Sodium

gas bromide

2K + Br2

2LiBr

Potassium Bromine Potassium gas bromide

5. Therefore, alkali metals have similar chemical properties.

Alkali metals have one valence electron in their outermost occupied shells. Each of them reacts by donating one electron from its outermost occupied shell to form an ion with a charge of +1, thus achieving the stable electron arrangement of the atom of noble gas.

Li

( Li+ + 1e-2.1

2

Na

( Na+ + 1e- 2.8.1

2.8

K

( K+ + 1e- 2.8.8.1

2.8.86. The reactivity of Group 1 elements increases down the group.

Going down Group 1, the atomic size (atomic radius) increases. The single valence electron in the outermost occupied shell becomes further away from the nucleus

Hence, the attraction between the nucleus and the valence electron becomes weaker

Therefore, it is easier for the atom to donate the single valence electron to achieve the stable electron arrangement. Safety precautions in handling Group 1 elements

Alkali metals are very reactive. Safety precautions must be taken when handling alkali metals. The elements must be stored in paraffin oil in bottles Do not hold alkali metals with your bare hands Use forceps to handle them Wear safety goggles Wear safety gloves

Use a small piece of alkali metal when conducting experimentsHw: QR C pg. 69 no. 1,2,3

Kamal Ariffin B Saaim

Smkdbl

http://kemhawk.webs.com/

GROUP 1

Why alkali metals have similar chemical properties?

Why The reactivity of Group 1 elements increases down the group?

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