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group i - the alkali metals


GROUP 1 The alkali metals
A guide for GCSE students

KNOCKHARDY PUBLISHING

2010
SPECIFICATIONS

GROUP I
INTRODUCTION
This Powerpoint show is one of several produced to help students understand selected GCSE Chemistry topics. It is based on the requirements of the AQA specification but is suitable for other examination boards. Individual students may use the material at home for revision purposes and it can also prove useful for classroom teaching with an interactive white board. Additional Powerpoints, and the full range of AS and A2 Chemistry topics, are available from the KNOCKHARDY WEBSITE at...

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All diagrams and animations in this Powerpoint are original and created by Jonathan Hopton. Permission must be obtained for their use in any commercial work.

GROUP I
CONTENTS
? Introduction ? Group trends ? Group similarities ? Flame tests ? Reaction with water ? Reaction with halogens ? Summary ? Quick quiz

INTRODUCTION

INTRODUCTION
THE ALKALI METALS ARE IN GROUP I OF THE PERIODIC TABLE
0 Group 1 Li Na K 2 3 4 5 6 7

Rb
Cs Fr

INTRODUCTION
THE ALKALI METALS ARE IN GROUP I OF THE PERIODIC TABLE
0 Group 1 Li Na K 2 3 4 5 6 7

Rb
Cs Fr

THEY ARE VERY REACTIVE METALS AND HAVE ELECTRONIC CONFIGURATIONS WITH ONE ELECTRON IN THE OUTER SHELL

GROUP PROPERTIES
GENERAL

? ? ? ? ?

metals exist as separate diatomic molecules… eg Cl2 have one electron in their outer shell form positive ions with a 1+ charge vigorous reaction with water and halides

GROUP PROPERTIES
GENERAL

? ? ? ? ?

metals exist as separate diatomic molecules… eg Cl2 have one electron in their outer shell form positive ions with a 1+ charge vigorous reaction with water and halides

TRENDS

? ? ? ? ?

melting point hardness electronic configuration atomic size ionic size

? reactivity

GROUP TRENDS

GROUP TRENDS
APPEARANCE
Li Appearance Grey solid Na Grey solid K Grey solid Rb Grey solid Cs Grey solid

Density / gcm-3
Flame test

0.53
Crimson

0.97
Yellow

0.86
Lilac

1.53
Red-violet

1.87
Blue-violet

GROUP TRENDS
APPEARANCE
Li Appearance Grey solid Na Grey solid K Grey solid Rb Grey solid Cs Grey solid

Density / gcm-3
Flame test

0.53
Crimson

0.97
Yellow

0.86
Lilac

1.53
Red-violet

1.87
Blue-violet

MELTING POINT
Li Melting point / °C 180.7 Na 98 K 63.8 Rb 39.2 Cs 43.2

DECREASES down Group as the atoms get larger

GROUP TRENDS
ELECTRONIC CONFIGURATION
Li Atomic Number 3 Na 11 K 19 Rb 37 Cs 55

Configuration

2,1

2,8,1

2,8,8,1

2,8,18,8,1

2,8,18,18,8,1

GROUP TRENDS
ELECTRONIC CONFIGURATION
Li Atomic Number 3 Na 11 K 19 Rb 37 Cs 55

Configuration

2,1

2,8,1

2,8,8,1

2,8,18,8,1

2,8,18,18,8,1

? electrons go into shells further from the nucleus

3+

11+

19+

LITHIUM 2,1

SODIUM 2,8,1

POTASSIUM 2,8,8,1

GROUP TRENDS
ATOMIC RADIUS
Li Atomic radius / nm 0.152 Na 0.185 K 0.227 Rb 0.247 Cs 0.265

Li

Na

K

Rb

Cs

GROUP TRENDS
ATOMIC RADIUS
Li Atomic radius / nm 0.152 Na 0.185 K 0.227 Rb 0.247 Cs 0.265

Li

Na

K

Rb

Cs

ATOMIC RADIUS

INCREASES down Group

? the greater the atomic number the more electrons there are; these go into shells increasingly further from the nucleus

GROUP TRENDS
ATOMIC & IONIC RADIUS
Li Atomic radius / nm 0.152 Na 0.185 K 0.227 Rb 0.247 Cs 0.265

Li

Na

K

Rb

Cs

Li+ Ionic radius / nm 0.068
Li+

Na+ 0.098
Na+

K+ 0.133

Rb+ 0.148

Cs+ 0.167

K+

Rb+

Cs+

IONIC RADIUS

INCREASES down Group

? ions are smaller than atoms - the removal of an electron means that there are now fewer shells

GROUP SIMILARITIES

GROUP SIMILARITIES
ION FORMATION
Li Ion Configuration Li+ 2 Na Na+ 2,8 K K+ 2,8,8 Rb Rb+ 2,8,18,8 Cs Cs+ 2,8,18,18,8

GROUP SIMILARITIES
ION FORMATION
Li Ion Configuration Li+ 2 Na Na+ 2,8 K K+ 2,8,8 Rb Rb+ 2,8,18,8 Cs Cs+ 2,8,18,18,8

? atoms ‘lose’ one electron to form a positive ion of charge 1+ ? ions are smaller than atoms ? the larger the atom the easier it forms an ion because the electron being removed is further from the nucleus

GROUP SIMILARITIES
ION FORMATION
Li Ion Configuration Li+ 2 Na Na+ 2,8 K K+ 2,8,8 Rb Rb+ 2,8,18,8 Cs Cs+ 2,8,18,18,8

? atoms ‘lose’ one electron to form a positive ion of charge 1+ ? ions are smaller than atoms ? the larger the atom the easier it forms an ion because the electron being removed is further from the nucleus

SODIUM ATOM 11 PROTONS 11 ELECTRONS

11+

SODIUM ION 11 PROTONS 10 ELECTRONS

11+

GROUP SIMILARITIES
ION FORMATION
Li Ion Configuration Li+ 2 Na Na+ 2,8 K K+ 2,8,8 Rb Rb+ 2,8,18,8 Cs Cs+ 2,8,18,18,8

? atoms ‘lose’ one electron to form a positive ion of charge 1+ ? ions are smaller than atoms ? the larger the atom the easier it forms an ion because the electron being removed is further from the nucleus

REACTIVITY
Li Na K Rb Cs

Increasingly reactive

? reactivity increases down the Group as atoms get larger

FLAME TESTS

FLAME TESTS
? ? ? ? SOME METALS CAN BE IDENTIFIED BY FLAME TESTS A SAMPLE OF ONE OF THEIR SALTS IS PLACED IN A BUNSEN FLAME THE HEAT OF THE FLAME GIVES ELECTRONS ENERGY THE ELECTRONS THEN GIVE OUT ENERGY AS LIGHT

FLAME TESTS
? ? ? ? SOME METALS CAN BE IDENTIFIED BY FLAME TESTS A SAMPLE OF ONE OF THEIR SALTS IS PLACED IN A BUNSEN FLAME THE HEAT OF THE FLAME GIVES ELECTRONS ENERGY THE ELECTRONS THEN GIVE OUT ENERGY AS LIGHT

NORMAL BUNSEN

Cu
BLUEGREEN

Na
BRIGHT YELLOW

Ba
APPLE GREEN

K
LILAC

Ca
BRICK RED

FLAME TESTS
? ? ? ? ? SOME METALS CAN BE IDENTIFIED BY FLAME TESTS A SAMPLE OF ONE OF THEIR SALTS IS PLACED IN A BUNSEN FLAME THE HEAT OF THE FLAME GIVES ELECTRONS ENERGY THE ELECTRONS THEN GIVE OUT ENERGY AS LIGHT A LINE SPECTRUM IS PRODUCED

FLAME TESTS
? ? ? ? ? SOME METALS CAN BE IDENTIFIED BY FLAME TESTS A SAMPLE OF ONE OF THEIR SALTS IS PLACED IN A BUNSEN FLAME THE HEAT OF THE FLAME GIVES ELECTRONS ENERGY THE ELECTRONS THEN GIVE OUT ENERGY AS LIGHT A LINE SPECTRUM IS PRODUCED

CONTINUOUS SPECTRUM

FLAME TESTS
? ? ? ? ? SOME METALS CAN BE IDENTIFIED BY FLAME TESTS A SAMPLE OF ONE OF THEIR SALTS IS PLACED IN A BUNSEN FLAME THE HEAT OF THE FLAME GIVES ELECTRONS ENERGY THE ELECTRONS THEN GIVE OUT ENERGY AS LIGHT A LINE SPECTRUM IS PRODUCED

CONTINUOUS SPECTRUM

LINE SPECTRUM

FLAME TESTS
? ? ? ? ? SOME METALS CAN BE IDENTIFIED BY FLAME TESTS A SAMPLE OF ONE OF THEIR SALTS IS PLACED IN A BUNSEN FLAME THE HEAT OF THE FLAME GIVES ELECTRONS ENERGY THE ELECTRONS THEN GIVE OUT ENERGY AS LIGHT A LINE SPECTRUM IS PRODUCED

CONTINUOUS SPECTRUM

LINE SPECTRUM

EACH METAL HAS ITS OWN CHARACTERISTIC LINE SPECTRUM

REACTIONS OF ALKALI METALS

REACTIONS OF ALKALI METALS
REACTIVITY INCREASES DOWN THE GROUP

The further the outer shell electron is from the nucleus, the easier it is to remove and the easier it becomes to form a positive ion.
Because of this, alkali metals get more reactive as you go down the group.

REACTIONS OF ALKALI METALS
REACTIVITY INCREASES DOWN THE GROUP

The further the outer shell electron is from the nucleus, the easier it is to remove and the easier it becomes to form a positive ion.
Because of this, alkali metals get more reactive as you go down the group.
GETS INCREASINGLY EASIER TO REMOVE THE OUTER SHELL ELECTRON

3+ 11+ 19+

LITHIUM 2,1
SODIUM 2,8,1 POTASSIUM 2,8,8,1

REACTION WITH WATER

REACTION WITH WATER
1. 2. 3. 4. 5. 6. GROUP I METALS REACT WITH COLD WATER THE REACTIVITY INCREASES DOWN THE GROUP HYDROGEN GAS IS PRODUCED A METAL HYDROXIDE IS FORMED GROUP I HYDROXIDES ARE WHITE CRYSTALLINE SOLIDS THE HYDROXIDES DISSOLVE IN WATER TO GIVE ALKALINE SOLUTIONS

REACTION WITH WATER
1. 2. 3. 4. 5. 6. GROUP I METALS REACT WITH COLD WATER THE REACTIVITY INCREASES DOWN THE GROUP HYDROGEN GAS IS PRODUCED A METAL HYDROXIDE IS FORMED GROUP I HYDROXIDES ARE WHITE CRYSTALLINE SOLIDS THE HYDROXIDES DISSOLVE IN WATER TO GIVE ALKALINE SOLUTIONS

LITHIUM
FLOATS

STEADILY GIVES OFF A GAS
CLEAR ALKALINE SOLUTION LEFT LITHIUM HYDROXIDE FORMED

REACTION WITH WATER
1. 2. 3. 4. 5. 6. GROUP I METALS REACT WITH COLD WATER THE REACTIVITY INCREASES DOWN THE GROUP HYDROGEN GAS IS PRODUCED A METAL HYDROXIDE IS FORMED GROUP I HYDROXIDES ARE WHITE CRYSTALLINE SOLIDS THE HYDROXIDES DISSOLVE IN WATER TO GIVE ALKALINE SOLUTIONS

SODIUM
FLOATS AND MOVES ABOUT

MELTS TO A SPHERE
GIVES OFF A GAS YELLOW FLAME CLEAR ALKALINE SOLUTION LEFT
ANIMATION

SODIUM HYDROXIDE FORMED

REACTION WITH WATER
1. 2. 3. 4. 5. 6. GROUP I METALS REACT WITH COLD WATER THE REACTIVITY INCREASES DOWN THE GROUP HYDROGEN GAS IS PRODUCED A METAL HYDROXIDE IS FORMED GROUP I HYDROXIDES ARE WHITE CRYSTALLINE SOLIDS THE HYDROXIDES DISSOLVE IN WATER TO GIVE ALKALINE SOLUTIONS

POTASSIUM
FLOATS AND MOVES ABOUT

VIGOROUS REACTION
GIVES OFF A GAS LILAC FLAME CLEAR ALKALINE SOLUTION LEFT
ANIMATION

POTASSIUM HYDROXIDE FORMED

REACTION WITH WATER
1. 2. 3. 4. 5. 6. GROUP I METALS REACT WITH COLD WATER THE REACTIVITY INCREASES DOWN THE GROUP HYDROGEN GAS IS PRODUCED A METAL HYDROXIDE IS FORMED GROUP I HYDROXIDES ARE WHITE CRYSTALLINE SOLIDS THE HYDROXIDES DISSOLVE IN WATER TO GIVE ALKALINE SOLUTIONS

RUBIDIUM
WHAT WOULD YOU EXPECT?

REACTION WITH WATER- Equations
Write out the word equation

SODIUM +

WATER

SODIUM HYDROXIDE +

HYDROGEN

REACTION WITH WATER- Equations
Write out the word equation

SODIUM +

WATER

SODIUM HYDROXIDE +

HYDROGEN

Write out the formulae

Na

+

H 2O

NaOH

+

H2

REACTION WITH WATER- Equations
Write out the word equation

SODIUM +

WATER

SODIUM HYDROXIDE +

HYDROGEN

Write out the formulae

Na

+

H 2O

NaOH

+

H2

If the equation doesn’t balance, multiply the formulae until it does

REACTION WITH WATER- Equations
Write out the word equation

SODIUM +

WATER

SODIUM HYDROXIDE +

HYDROGEN

Write out the formulae

Na

+

H 2O

NaOH

+

H2

If the equation doesn’t balance, multiply the formulae until it does

Na

+

2H2O

NaOH

+

H2

REACTION WITH WATER- Equations
Write out the word equation

SODIUM +

WATER

SODIUM HYDROXIDE +

HYDROGEN

Write out the formulae

Na

+

H 2O

NaOH

+

H2

If the equation doesn’t balance, multiply the formulae until it does

Na Na

+ +

2H2O 2H2O

NaOH 2NaOH

+ +

H2 H2

REACTION WITH WATER- Equations
Write out the word equation

SODIUM +

WATER

SODIUM HYDROXIDE +

HYDROGEN

Write out the formulae

Na

+

H 2O

NaOH

+

H2

If the equation doesn’t balance, multiply the formulae until it does

Na Na 2Na

+ + +

2H2O 2H2O 2H2O

NaOH 2NaOH 2NaOH

+ + +

H2 H2 H2

The equation is balanced.

REACTION WITH WATER- Equations
2Li
LITHIUM +

+

2H2O

2LiOH

+

H2

WATER

LITHIUM HYDROXIDE + HYDROGEN

REACTION WITH WATER- Equations
2Li
LITHIUM +

+

2H2O

2LiOH

+

H2

WATER

LITHIUM HYDROXIDE + HYDROGEN

2Na
SODIUM +

+

2H2O
WATER

2NaOH

+

H2

SODIUM HYDROXIDE + HYDROGEN

REACTION WITH WATER- Equations
2Li
LITHIUM +

+

2H2O

2LiOH

+

H2

WATER

LITHIUM HYDROXIDE + HYDROGEN

2Na
SODIUM +

+

2H2O
WATER

2NaOH

+

H2

SODIUM HYDROXIDE + HYDROGEN

POTASSIUM

+

WATER

RUBIDIUM

+

WATER

REACTION WITH WATER- Equations
2Li
LITHIUM +

+

2H2O

2LiOH

+

H2

WATER

LITHIUM HYDROXIDE + HYDROGEN

2Na
SODIUM +

+

2H2O
WATER

2NaOH

+

H2

SODIUM HYDROXIDE + HYDROGEN

2K
POTASSIUM

+
+

2H2O
WATER

2KOH

+

H2

POTASSIUM HYDROXIDE + HYDROGEN

2Rb
RUBIDIUM

+
+

2H2O
WATER

2RbOH

+

H2

RUBIDIUM HYDROXIDE + HYDROGEN

REACTION WITH HALOGENS

REACTION WITH HALOGENS
ALKALI METALS REACT VIGOROUSLY WITH HALOGENS TO FORM IONIC COMPOUNDS CALLED HALIDES.

REACTION WITH HALOGENS
ALKALI METALS REACT VIGOROUSLY WITH HALOGENS TO FORM IONIC COMPOUNDS CALLED HALIDES.

SODIUM

+

CHLORINE

SODIUM CHLORIDE

REACTION WITH HALOGENS
ALKALI METALS REACT VIGOROUSLY WITH HALOGENS TO FORM IONIC COMPOUNDS CALLED HALIDES.

SODIUM

+

CHLORINE

SODIUM CHLORIDE

POTASSIUM

+

CHLORINE

REACTION WITH HALOGENS
ALKALI METALS REACT VIGOROUSLY WITH HALOGENS TO FORM IONIC COMPOUNDS CALLED HALIDES.

SODIUM

+

CHLORINE

SODIUM CHLORIDE

POTASSIUM

+

CHLORINE

POTASSIUM CHLORIDE

REACTION WITH HALOGENS
ALKALI METALS REACT VIGOROUSLY WITH HALOGENS TO FORM IONIC COMPOUNDS CALLED HALIDES.

SODIUM

+

CHLORINE

SODIUM CHLORIDE

POTASSIUM

+ +

CHLORINE

POTASSIUM CHLORIDE

SODIUM

BROMINE

REACTION WITH HALOGENS
ALKALI METALS REACT VIGOROUSLY WITH HALOGENS TO FORM IONIC COMPOUNDS CALLED HALIDES.

SODIUM

+

CHLORINE

SODIUM CHLORIDE

POTASSIUM

+ +

CHLORINE

POTASSIUM CHLORIDE

SODIUM

BROMINE

SODIUM BROMIDE

REACTION WITH HALOGENS - Equations

Na
SODIUM

+

Cl2
CHLORINE

NaCl
SODIUM CHLORIDE

REACTION WITH HALOGENS - Equations

Na
SODIUM

+

Cl2
CHLORINE

NaCl
SODIUM CHLORIDE

The equation doesn’t balance - multiply the formulae until it does

REACTION WITH HALOGENS- Equations

Na
SODIUM

+

Cl2
CHLORINE

NaCl
SODIUM CHLORIDE

2Na
SODIUM

+

Cl2

2NaCl
SODIUM CHLORIDE

CHLORINE

The equation is balanced

FORMATION OF SODIUM CHLORIDE

Na

Cl

SODIUM ATOM 2,8,1
11 protons; 11 electrons

CHLORINE ATOM 2,8,7
17 protons; 17 electrons

PRESS THE SPACE BAR TO START THE ANIMATION

FORMATION OF SODIUM CHLORIDE

+ Na

Cl

SODIUM ION 2,8
11 protons; 10 electrons

CHLORIDE ION 2,8,8
17 protons; 18 electrons

both species now have ‘full’ outer shells; ie they have the electronic configuration of a noble gas

FORMATION OF SODIUM CHLORIDE

+ Na

Cl

SODIUM ION 2,8

CHLORIDE ION 2,8,8

Na
2,8,1

Na+
2,8

+

e?
ELECTRON TRANSFERRED

Cl
2,8,7

+

e?

Cl?
2,8,8

GROUP I - SUMMARY
LITHIUM SYMBOL ELECTRONIC CONFIGURATION HARDNESS DENSITY (Compared to water) METHOD OF STORAGE MELTING POINT SODIUM POTASSIUM

Li 2,1
CAN BE CUT JUST OVER HALF

Na 2,8,1
EASY TO CUT JUST LIGHTER

K

● 2,8,8,1 ●●●
VERY EASY TO CUT A BIT LIGHTER

IN OIL

IN OIL

IN OIL

181°C

91°C

63°C

REACTION WITH OXYGEN IN THE AIR

Tarnishes quickly

Tarnishes very quickly

Tarnishes very quickly

FORMULA OF OXIDE
REACTION WITH WATER PRODUCTS

Li20 steady
LITHIUM HYDROXIDE & HYDROGEN

Na2O fast
SODIUM HYDROXIDE & HYDROGEN

K2O very fast
POTASSIUM HYDROXIDE & HYDROGEN

QUICK QUIZ
1. 2. 3. 4. 5. 6. 7. 8. 9. ELEMENTS IN GROUP I ARE KNOWN AS THE ………. METALS WHAT ARE THE NAMES OF THE ELEMENTS? HOW DOES THE ATOMIC NUMBER CHANGE DOWN THE GROUP? HOW DOES THE MELTING POINT CHANGE? HOW DOES THE ATOMIC SIZE (RADIUS) CHANGE? HOW MANY ELECTRONS DO THEY HAVE IN THE OUTER SHELL? WHAT TYPE OF ION DO THEY FORM? HOW DOES THEIR REACTIVITY CHANGE DOWN THE GROUP? WHAT TYPE OF COMPOUND DO THEY FORM WITH NON-METALS?

10. DO THEIR HYDROXIDES DISSOLVE IN WATER?
11. WHAT TYPE OF SOLUTION DO THEIR HYDROXIDES GIVE? 12. HOW CAN YOU EXPLAIN THEIR RELATIVE REACTIVITY IN TERMS OF THE ATOMIC STRUCTURE?

QUICK QUIZ - ANSWERS
1. 2. 3. 4. 5. 6. 7. 8. 9. ALKALI METALS LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, FRANCIUM ATOMIC NUMBER INCREASES DOWN THE GROUP MELTING POINT DECREASES DOWN THE GROUP ATOMIC SIZE INCREASES DOWN THE GROUP ALL HAVE ONE ELECTRON IN THE OUTER SHELL (ENERGY LEVEL) FORM IONS OF CHARGE +1 REACTIVITY INCREASES DOWN THE GROUP FORM IONIC COMPOUNDS WITH NON-METALS

10. HYDROXIDES DISSOLVE IN WATER
11. HYDROXIDES FORM ALKALINE SOLUTIONS 12. AS THE ATOMS GET BIGGER THE OUTER SHELL ELECTRON IS FURTHER FROM THE NUCLEUS SO IS EASIER TO REMOVE; THE METALS BECOME MORE REACTIVE

GROUP 1 The alkali metals
THE END

? 2011 KNOCKHARDY PUBLISHING & JONATHAN HOPTON


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