group 1 the alkali metals national 5 chemistry knockhardy publishing

GROUP 1GROUP 1The alkali metalsThe alkali metals

National 5 ChemistryNational 5 Chemistry

KNOCKHARDY PUBLISHINGKNOCKHARDY PUBLISHING

GROUP IGROUP I

INTRODUCTION

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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.

CONTENTSCONTENTS

• Introduction

• Group trends

• Group similarities

• Flame tests

• Reaction with water

• Reaction with halogens

• Summary

• Quick quiz

GROUP IGROUP I

INTRODUCTIONINTRODUCTION


THE ALKALI METALS ARE IN GROUP I OF THE PERIODIC TABLE

Group 1 2 3 4 5 6 7

0

Li

Na

K

Rb

Fr

Cs


THE ALKALI METALS ARE IN GROUP I OF THE PERIODIC TABLE

Group 1 2 3 4 5 6 7

0

Li

Na

K

Rb

Fr

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

Cs

GROUP PROPERTIESGROUP 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 PROPERTIESGROUP 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 TRENDSGROUP TRENDS


APPEARANCEAPPEARANCE

Density / gcm-3

Li Na K Rb

0.53 0.97 0.86 1.53

Cs

1.87

Appearance Grey solid Grey solid Grey solid Grey solid Grey solid

Flame test Crimson Yellow Lilac Red-violet Blue-violet


DECREASES down Group as the atoms get larger

APPEARANCEAPPEARANCE

MELTING POINTMELTING POINT

Melting point / °C

Li Na K Rb

180.7 98 63.8 39.2

Cs

43.2

Density / gcm-3

Li Na K Rb

0.53 0.97 0.86 1.53

Cs

1.87

Appearance Grey solid Grey solid Grey solid Grey solid Grey solid

Flame test Crimson Yellow Lilac Red-violet Blue-violet


Configuration

ELECTRONIC CONFIGURATIONELECTRONIC CONFIGURATION

Atomic Number

Li Na K Rb

3 11 19 37

Cs

55

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

Configuration

ELECTRONIC CONFIGURATIONELECTRONIC CONFIGURATION

Atomic Number

Li Na K Rb

3 11 19 37

Cs

55

2,1 2,8,1 2,8,8,1 2,8,18,8,1 2,8,18,18,8,1

11+3+ 19+

LITHIUM2,1

SODIUM2,8,1

POTASSIUM2,8,8,1


Li Na K Rb

ATOMIC RADIUSATOMIC RADIUS

0.152 0.185 0.227 0.247Atomic radius / nm

Cs

0.265

LiRbNa K 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

Li Na K Rb

ATOMIC RADIUSATOMIC RADIUS

0.152 0.185 0.227 0.247Atomic radius / nm

Cs

0.265

LiRbNa K Cs


ATOMIC & IONIC RADIUSATOMIC & IONIC RADIUS

Li Na K Rb

0.152 0.185 0.227 0.247Atomic radius / nm

Cs

0.265

LiRbNa K Cs

Li+ Na+ K+ Rb+

0.068 0.098 0.133 0.148Ionic radius / nm

Cs+

0.167

Li+

Rb+Na+K+

Cs+

IONIC RADIUS INCREASES down Group

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

GROUP GROUP SIMILARITIESSIMILARITIES


ION FORMATIONION FORMATION

Configuration

Ion

Li Na K Rb

Li+ Na+ K+ Rb+

Cs

Cs+

2 2,8 2,8,8 2,8,18,8 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

Configuration

Ion

Li Na K Rb

Li+ Na+ K+ Rb+

Cs

Cs+

2 2,8 2,8,8 2,8,18,8 2,8,18,18,8






Configuration

Ion

Li Na K Rb

Li+ Na+ K+ Rb+

Cs

Cs+

2 2,8 2,8,8 2,8,18,8 2,8,18,18,8

11+ 11+SODIUM ATOM11 PROTONS

11 ELECTRONS

SODIUM ION11 PROTONS

10 ELECTRONS






• reactivity increases down the Group as atoms get larger

Increasingly reactive

Configuration

Ion

Li Na K Rb

Li+ Na+ K+ Rb+

Cs

Cs+

2 2,8 2,8,8 2,8,18,8 2,8,18,18,8

Li Na K Rb Cs

REACTIVITYREACTIVITY

FLAME TESTSFLAME 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






Cu Na Ba K CaNORMALBUNSEN

BLUE- BRIGHT APPLE LILAC BRICKGREEN YELLOW GREEN RED






• A LINE SPECTRUM IS PRODUCED


CONTINUOUS SPECTRUM







CONTINUOUS SPECTRUM

LINE SPECTRUM







CONTINUOUS SPECTRUM

LINE SPECTRUM

EACH METAL HAS ITS OWN CHARACTERISTIC LINE SPECTRUM






REACTIONS OF ALKALI METALSREACTIONS 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.


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.

LITHIUM2,1

11+

3+

SODIUM2,8,1

19+

POTASSIUM2,8,8,1


GETS INCREASINGLY EASIER TO REMOVE THE OUTER SHELL ELECTRON

REACTION WITH WATERREACTION WITH WATER


1. GROUP I METALS REACT WITH COLD WATER

2. THE REACTIVITY INCREASES DOWN THE GROUP

3. HYDROGEN GAS IS PRODUCED

4. A METAL HYDROXIDE IS FORMED

5. GROUP I HYDROXIDES ARE WHITE CRYSTALLINE SOLIDS

6. THE HYDROXIDES DISSOLVE IN WATER TO GIVE ALKALINE SOLUTIONS








LITHIUM

FLOATS

STEADILY GIVES OFF A GAS

CLEAR ALKALINE SOLUTION LEFT

LITHIUM HYDROXIDE FORMED








SODIUM

FLOATS AND MOVES ABOUT

MELTS TO A SPHERE

GIVES OFF A GAS

YELLOW FLAME


SODIUM HYDROXIDE FORMEDANIMATION








POTASSIUM

FLOATS AND MOVES ABOUT

VIGOROUS REACTION

GIVES OFF A GAS

LILAC FLAME


POTASSIUM HYDROXIDE FORMEDANIMATION








RUBIDIUM

WHAT WOULD YOU EXPECT?

REACTION WITH WATER- EquationsREACTION WITH WATER- Equations

SODIUM + WATER SODIUM HYDROXIDE + HYDROGEN

Write out the word equation

Na + H2O NaOH + H2



Write out the formulae


Na + H2O NaOH + H2




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


Na + H2O NaOH + H2




Na + 2H2O NaOH + H2



Na + H2O NaOH + H2



Na + 2H2O 2NaOH + H2


Na + 2H2O NaOH + H2



Na + H2O NaOH + H2



Na + 2H2O 2NaOH + H2


Na + 2H2O NaOH + H2


2Na + 2H2O 2NaOH + H2

The equation is balanced.


LITHIUM + WATER LITHIUM HYDROXIDE + HYDROGEN

2Li + 2H2O 2LiOH + H2




POTASSIUM + WATER

RUBIDIUM + WATER






POTASSIUM + WATER POTASSIUM HYDROXIDE +

HYDROGEN

2K + 2H2O 2KOH + H2

RUBIDIUM + WATER RUBIDIUM HYDROXIDE +

HYDROGEN

2Rb + 2H2O 2RbOH + H2




REACTION WITH HALOGENSREACTION WITH HALOGENS


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



SODIUM CHLORINE SODIUM CHLORIDE+




POTASSIUM CHLORINE +




POTASSIUM CHLORINE POTASSIUM CHLORIDE+





SODIUM BROMINE+





SODIUM BROMINE SODIUM BROMIDE+

REACTION WITH HALOGENS - EquationsREACTION WITH HALOGENS - Equations

Na + Cl2 NaCl

SODIUM CHLORINE SODIUM CHLORIDE

REACTION WITH HALOGENS - EquationsREACTION WITH HALOGENS - Equations

Na + Cl2 NaCl

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


REACTION WITH HALOGENS- EquationsREACTION WITH HALOGENS- Equations

2Na + Cl2 2NaCl

Na + Cl2 NaCl



The equation is balancedThe equation is balanced

Cl

SODIUM ATOM2,8,1

Na

CHLORINE ATOM2,8,7

11 protons; 11 electrons 17 protons; 17 electrons

FORMATION OF SODIUM CHLORIDEFORMATION OF SODIUM CHLORIDE

PRESS THE SPACE BAR TO START THE ANIMATION

Cl

SODIUM ION2,8

Na

CHLORIDE ION2,8,8

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

+

11 protons; 10 electrons 17 protons; 18 electrons


Cl

SODIUM ION2,8

Na

CHLORIDE ION2,8,8

Na Na+ + e¯2,8,1 2,8

ELECTRON TRANSFERRED

Cl + e¯ Cl¯2,8,7 2,8,8

+


SYMBOL

ELECTRONIC CONFIGURATION

HARDNESS

DENSITY(Compared to water)

Li

CAN BE CUT

JUST OVER HALF

POTASSIUM

Na

● ● ● ●

LITHIUM SODIUM

K

METHOD OF STORAGE

MELTING POINT

IN OIL

181°C

IN OIL

91°C

IN OIL

63°C

JUST LIGHTER A BIT LIGHTER

REACTION WITH OXYGEN IN THE AIR Tarnishes quickly Tarnishes very quickly Tarnishes very quickly

REACTION WITH WATER steady fast very fast

FORMULA OF OXIDE Li20 Na2O K2O

PRODUCTS LITHIUM HYDROXIDE & HYDROGEN

SODIUM HYDROXIDE & HYDROGEN

POTASSIUM HYDROXIDE & HYDROGEN

EASY TO CUT VERY EASY TO CUT

2,1 2,8,1 2,8,8,1

GROUP I - SUMMARYGROUP I - SUMMARY

QUICK QUIZQUICK QUIZ

1. ELEMENTS IN GROUP I ARE KNOWN AS THE ………. METALS

2. WHAT ARE THE NAMES OF THE ELEMENTS?

3. HOW DOES THE ATOMIC NUMBER CHANGE DOWN THE GROUP?

4. HOW DOES THE MELTING POINT CHANGE?

5. HOW DOES THE ATOMIC SIZE (RADIUS) CHANGE?

6. HOW MANY ELECTRONS DO THEY HAVE IN THE OUTER SHELL?

7. WHAT TYPE OF ION DO THEY FORM?

8. HOW DOES THEIR REACTIVITY CHANGE DOWN THE GROUP?

9. 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 - ANSWERSQUICK QUIZ - ANSWERS

1. ALKALI METALS

2. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, FRANCIUM

3. ATOMIC NUMBER INCREASES DOWN THE GROUP

4. MELTING POINT DECREASES DOWN THE GROUP

5. ATOMIC SIZE INCREASES DOWN THE GROUP

6. ALL HAVE ONE ELECTRON IN THE OUTER SHELL (ENERGY LEVEL)

7. FORM IONS OF CHARGE +1

8. REACTIVITY INCREASES DOWN THE GROUP

9. 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 1GROUP 1The alkali metalsThe alkali metals

THE ENDTHE END

© 2011 © 2011 KNOCKHARDY PUBLISHING & JONATHAN HOPTON KNOCKHARDY PUBLISHING & JONATHAN HOPTON

group 1 the alkali metals national 5 chemistry knockhardy publishing

Documents

group ions

group trends electrons

introduction slide

rb fr cs slide

cs li na

atomic radius nm cs

outer shell cs slide

violet slide