What Family of Elements Are the Most Reactive

Physical and Chemical Backdrop of Grouping 1 Elements

Grouping 1 Elements: The Brine Metals

The elements in Group 1 are:

These elements are known as brine metals.

Concrete Properties of Group one Elements

1. Table shows some properties of Group 1 elements.

Chemical element	Proton number	Nucleon number	Density (g cm-iii)	Hardness (Brinell)	Melting signal (°C)	Boiling betoken (°C)	Atomic radius (nm)	Electro negativity
Lithium	3	vii	0.53	0.06	181	1347	0.xv	one.0
Sodium	11	23	0.97	0.07	98	886	0.19	0.9
Potassium	19	39	0.86	0.04	64	774	0.23	0.8
Rubidium	37	85	1.53	0.03	39	688	0.25	0.eight
Caesium	55	133	1.87	0.02	28	678	0.26	0.7
Francium	87	223	2.40	?	27	677	0,29	0.seven

2. Full general concrete properties of Group i elements:

• • Alkali metals are greyness solids with shiny silvery surfaces when freshly cut.
  • These surfaces plow tedious when exposed to air.
  • This is because alkali metals are very reactive. They react rapidly with oxygen and water vapour in the air when exposed.
• Alkali metals are soft solids and can be easily cut.
• Alkali metals accept low densities as compared to heavy metals such as iron and copper.
• Alkali metals are good conductors of heat and electricity.
• Brine metals have depression melting and boiling points equally compared to heavy metals such as copper and iron.

Table compares the melting and humid points of potassium (an brine metal) and copper (a heavy metal).

Element	Potassium	Copper
Melting point (°C)	64	1083
Humid point (°C)	774	2567

3. Tendency of change in the physical properties
The concrete backdrop of the elements vary gradually when going downwards Grouping 1 as shown in Table.

Grouping 1 elements	Tendency of change in the physical properties
	The atomic radius (diminutive size) of alkali metals increases graduallydown the group. Reason: The number of shellsoccupied with electrons increases downwards the group.	Although alkali metals have depression densities, the densities increase gradually down the group. For example: Lithium, sodium and potassium are less dense than water. Thus, these metals float on the h2o surface. Rubidium, caesium and francium are denser than water. Thus, these metals sink in water. Metal bail means the chemic bond that holds the atoms together in a metal.	Although alkali metals have low melting and humid points, the melting and boiling points subtract gradually down the group. Reason: As the atomic size increases down the grouping, the metallic bond between the atoms of alkali metals becomes weaker. Hence, less heat energy is required to overcome the weaker metallic bonding during melting or humid when going down the group.	Alkali metals become softer down the group.

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Chemical Properties of Group 1 Elements

1. Tabular array shows the electron arrangements of alkali metals.

Element	Electron arrangement
Lithium	2.one
Sodium	two.viii.i
Potassium	2.8.viii.1
Rubidium	2.8.18.eight.1
Caesium	2.8.18.18.viii.ane
Francium	2.8.eighteen.32.18.viii.1

ii. Similar chemical properties

• All brine metal showroom similar chemical backdrop.
• This is because all the atoms of alkali metals take one valence electron.

3. Reactivity

Alkali metals are very reactive.
Although brine metals showroom similar chemical properties, they differ in reactivity.
The reactivity of alkali metals increases when going down Group i.

The reactivity of an alkali metal is measured by how easily its atom loses its single valence electron to achieve a stable noble gas electron arrangement (duplet or octet electron organisation).


The easier an alkali metal cantlet releases its unmarried valence electron, the more than reactive is the alkali metallic.

Explanation:
The increase in reactivity of alkali metals down Group 1 can be explained as follows.

• All alkali metals have i valence electron.
• Each atom of an alkaline will release i valence electron during a chemical reaction to attain a stable duplet or octet electron arrangement. Hence, an ion with a accuse of+one is formed.
  • When going downwardly Group ane, the atomic size of brine metals increases.
  • The single valence electron becomes farther abroad from the nucleus and is screened by more inner shells containing electrons.
    
• This means that the effective nuclear charge felt by the single valence electron decreases when going down the group.
• This causes the bonny forces between the nucleus and the single valence electron go weaker, so the single valence electron is more weakly pulled by the nucleus.
• Hence, the unmarried valence electron can exist released more easily when going down the group.
• As a result, the reactivity of alkali metals increases downward the group.

4. As reducing agents

• Reducing agents are proficient electron donors in chemical reactions.
• Brine metals are skillful reducing agents because the single valence electron in the atom of each alkali metallic can exist easily released to reach a stable electron arrangement of a noble gas (adept electron donor).
  • The strength of alkali metals as reducing agents increases when going downwards Group 1.
    
  • This is considering the single valence electron of the alkali metals becomes much easier to be released when going down the grouping.

5. Electropositivity

• (a) Definition:
  Electropositivity of an chemical element is a measurement of the power of an cantlet to donate electrons to form a positive ion.
  • Brine metals are very electropositive.
  • This is because the atom of each brine metallic can release its single valence electron hands to form a positive ion.
• All the same, the electropositivity of alkali metals increases when going down Group 1.
  

This tin can exist explained as below:

• The atomic size of alkali metals increases from lithium to francium.
• The unmarried valence electron in the outermost occupied trounce becomes further away from the nucleus and is screened past more inner shells containing electrons.
• So, the attractive forces between the nucleus and the unmarried valence electron get weaker when going down Group one.
• This causes the single valence electron to exist released more easily when going down Grouping ane.
• As a result, the electropositivity of alkali metals increases when going downward the grouping.

6. Grouping 1 elements exhibit similar chemical properties in their reactions with

• h2o to liberate hydrogen gas and form metal hydroxide.
• oxygen to produce metal oxides.
• chlorine to produce metal chloride.
• bromine to produce metal bromide.

vii. To predict the properties of rubidium, caesium and francium

• Rubidium, caesium and francium are placed below potassium in Group one of the Periodic Table.
• Hence, rubidium, caesium and francium are expected to react with water, oxygen, chlorine or bromine in a like manner as potassium but these reactions are more vigorous (more reactive) than potassium.
• For example:
  

8. Solubility of the salts of brine metals

• Carbonate, nitrate, chloride, sulphate, bromide and iodide salts of brine metals are white solids.
• These salts are soluble in water. They dissolve in water to form colourless solutions.

nine. Safety precautions in treatment Group 1 elements

• Alkali metals are very reactive.
• Alkali metals, when exposed, tin can react with oxygen and water vapour in the air.
• Hence, brine metals such as lithium, sodium and potassium must be kept in alkane oil, whereas rubidium and caesium are stored in sealed glass tubes. This is to preclude them from reacting with oxygen and h2o vapour in the air.
• The post-obit prophylactic precautions must be taken when handling alkali metals.
  • Avoid holding the highly reactive alkali metals with your bare easily.
  • Wear safety goggles and gloves during an experiment.

Chemical Properties of Grouping ane Elements Experiment 1

Aim: To investigate the chemic backdrop of Group i metals in their reactions with h2o and oxygen.
Problem statement: How practise Grouping 1 metals react with water and oxygen?

A. Reactions of alkali metals with water

Hypothesis: When going down Group ane, alkali metals get more reactive in their reactions with h2o.
Variables:
(a) Manipulated variable : Unlike types of alkali metals
(b) Responding variable : Reactivity of alkali metals
(c) Controlled variables : H2o, size of alkali metals
Operational definition: An alkali metal that reacts more vigorously and apace with water is a more reactive metal. Materials: Minor pieces of lithium, sodium and potassium, distilled water, cherry-red litmus paper and filter paper.
Apparatus: Water troughs, small knife and forceps.
Safe Measure:
Do non touch the extremely reactive alkali metals with your blank hands.
Ever vesture safety goggles and gloves.
Procedure:
A. small piece of lithium is cut out using a knife.

1. The oil on the surface of lithium is removed by rolling it on a slice of filter paper.
2. The lithium is then placed slowly onto the water surface in a water trough with the aid of forceps, as shown in Figure.
   
3. All changes that occur are recorded.
4. When the reaction stops, the solution formed is tested with a piece of scarlet litmus paper.
5. Steps i to five are repeated using sodium and potassium respectively to supersede lithium.

Observations:

Alkali metallic	Observation
Lithium	Lithium moves slowly on the water surface with a soft 'hiss' sound. A colourless solution that turns red litmus paper blue is formed.
Sodium	Sodium melts to become a small sphere, moves rapidly and randomly on the water surface with a hiss' sound. A colourless solution that turns red litmus newspaper blue is formed.
Potassium	Potassium melts to become a small sphere, burns with a lilac flame, moves very rapidly and randomly on the h2o surface with 'hiss' and 'popular' sounds. A colourless solution that turns red litmus paper blue is formed.

Discussion:

1. The alkali metals buzz and push around on the water surface similar a hovercraft. This is due to the liberation of hydrogen gas as they react with h2o.
2. Lithium, sodium and potassium react with water to produce a colourless gas ('hissing' sound) and an alkaline solution (metallic hydroxide) that turns crimson litmus paper blue. Hence, lithium, sodium and potassium exhibit similar chemic properties.
3. The observations also show that the reactivity of the brine metals in their reactions with water increases from lithium → sodium → potassium.
4. Alkali metals react with water to produce a metal hydroxide solution (an alkaline solution) and hydrogen gas.
   

B. Reactions of alkali metals with oxygen

Hypothesis: When going down Group 1, alkali metals become more reactive in their reactions with oxygen.
Variables:
(a) Manipulated variable : Unlike types of alkali metals
(b) Responding variable : Reactivity of brine metals
(c) Controlled variables : Oxygen gas, size of alkali metals
Operational definition: An alkali metallic that burns more rapidly and vigorously in oxygen gas is a more reactive metal.
Materials: Minor pieces of lithium, sodium and potassium, filter paper, red litmus newspaper and three gas jars filled
with oxygen gas.
Apparatus: Forceps, gas jar spoon, small knife and Bunsen burner.
Procedure:

1. A pocket-size piece of lithium is cut out using a knife.
2. The oil on the surface of lithium is removed by roiling it on a piece of filter newspaper.
3. The lithium is then heated in a gas jar spoon until it starts to burn.
4. The gas jar spoon with the burning lithium is then rapidly lowered into a gas jar filled with oxygen gas, as shown in Figure.
   
5. The changes that occur are recorded.
6. When the reaction stops, 10 cm3 of distilled h2o is poured into the gas jar and shaken well.
7. The solution formed is then tested with a piece of scarlet litmus paper.
8. Steps i to 7 are repeated using sodium and potassium respectively to supersede iithium.

Observations:

Brine metal	Observation
Lithium	Lithium burns slowly with a red flame and liberates white fumes which become a white solid on cooling to room temperature. The white solid dissolves in water to produce a colourless solution. This solution turns red litmus paper blue.
Sodium	Sodium burns rapidly and brightly with a xanthous flame and liberates white fumes which become a white solid on cooling to room temperature. The white solid dissolves in water to produce a colourless solution. This solution turns red litmus newspaper blue.
Potassium	Potassium burns very rapidly and brightly with a lilac flame and liberates white fumes which become a white solid on cooling to room temperature. The white solid dissolves in water to produce a colourless solution. This solution turns reddish litmus paper blue.

Discussion:

1. Lithium, sodium and potassium burn in oxygen gas respectively to produce white fumes which then become a white solid (metallic oxide). The white solid dissolves in h2o to form an alkaline solution (metal hydroxide). Hence, information technology can exist inferred that these alkali metals exhibit similar chemical backdrop.
2. From the brightness of the flame and the speed of called-for, information technology can be inferred that the reactivity of the alkali metals in their reactions with oxygen gas increases from lithium → sodium → potassium.
3. All the brine metals react with oxygen gas when heated to produce white solid metal oxides.
   
4. The white solid metal oxides formed dissolve in water to produce metal hydroxide solutions which are alkaline.
   

Conclusion:
The brine metals exhibit like chemic properties in their reactions with water or oxygen gas. The reactivity of alkali metals increases downwardly Group 1. Hence, the hypothesis proposed can be accepted.

Chemical Properties of Group ane Elements Experiment 2

Aim: To investigate the chemical backdrop of Group 1 metals in their reactions with chlorine and bromine.
Problem statement: How do Grouping ane metals react with chlorine and bromine?
Hypothesis: When going downward Group 1, brine metals become more than reactive in their reactions with chlorine or bromine.
Variables:
(a) Manipulated variable : Unlike types of alkali metals
(b) Responding variable : Reactivity of brine metals
(c) Controlled variables : Chlorine and bromine, size of alkali metals
Operational definition: An brine metal that reacts more vigorously and rapidly with chlorine or bromine gas is a more reactive metal.
Materials: Small pieces of lithium, sodium and potassium, filter newspaper, three gas jars filled with chlorine gas and three gas jars filled with bromine vapour.
Apparatus: Bunsen burner, forceps, gas jar spoon and pocket-size knife.
Safety Measures:
Chlorine gas and bromine vapour are poisonous. Wear gloves and safety goggles when treatment these halogens.
Procedure:

1. A small piece of lithium is cut out using a knife.
2. The oil on the surface of lithium is removed past rolling it on a piece of filter paper.
3. The lithium is then heated in a gas jar spoon until it starts to fire.
4. The gas jar spoon with the burning lithium is and then speedily lowered into a gas jar filled with chlorine gas, as shown in Figure.
   
5. The changes that occur are recorded.
6. Steps one to 5 are repeated using sodium and potassium respectively to replace lithium.
7. Steps i to 6 are repeated using bromine vapour to supercede chlorine gas.

Observations:

Element of group i	Observation
	Chlorine gas	Bromine vapour
Lithium	Lithium burns slowly with a red flame and liberates white fumes which become a white solid at the finish of the reaction.	Lithium burns slowly with a ruby flame and liberates white fumes which become a white solid at the end of the reaction. The ruby-red-brown bromine vapour is decolourised.
Sodium	Sodium burns rapidly and brightly with a yellow flame and liberates white fumes which become a white solid at the end of the reaction.	Sodium burns rapidly and brightly with a yellow flame and liberates white fumes which become a white solid at the end of the reaction. The cherry-red-dark-brown bromine vapour is decolourised.
Potassium	Potassium burns very quickly and brightly with a lilac flame and liberates white fumes which get a white solid at the finish of the reaction.	Potassium burns very rapidly and brightly with a lilac flame and liberates white fumes which get a white solid at the stop of the reaction. The blood-red-brown bromine vapour is decolourised.

Discussion:

1. Lithium, sodium and potassium exhibit like chemical properties in their reactions with chlorine gas or bromine vapour. This is because all these alkali metals take one valence electron.
2. From the effulgence of the flame and the speed of burning, information technology can be inferred that the reactivity of alkali metals in their reactions with chlorine or bromine increases from lithium → sodium → potassium.
3. All alkali metals react with chlorine gas when heated to produce white solid metallic chlorides.
   
4. Alkaliali metals react with brorr ine vapour when heated to produce white solid metallic bromides.
   

Determination:
The alkali metals exhibit similar chemic properties in their reactions with chlorine gas or bromine vapour. The reactivity of alkali metals increases down Group 1. Hence, the hypothesis proposed can be accustomed.

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