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Basic Trends Across the Periodic Table 1) Draw a line in the middle of a piece of graph paper, separating the page into top and bottom. On the top, plot a graph of number of outer electrons and, in the same coordinate system, a second graph of number of protons (y-axis) vs. atomic number (x-axis). On the bottom plot a separate graph of atomic radius vs. atomic number. For each graph connect successive dots with straight lines. Also, ensure that identical atomic numbers are plotted on the same vertical position on the sheet (i.e. atomic number 1 in the top graph should be on the same line as atomic number 1 in the bottom graph). 2) Examine your graph of electron number vs. atomic number. a) Which elements are found at the main peaks on your graph (there should be 3)? What do these elements have in common? b) Which elements are found at the main valleys on your graph (there should be 3)? What do these elements have in common? 3) Examine your graph of atomic radius versus atomic number. a) Which elements are found at the peaks on your graph? What do these elements have in common? b) Which elements are found at the valleys on your graph? What do these elements have in common? 4) How are proton number and atomic radii related (i.e. as the proton number increases, what happens to the atomic radius)? Use this to explain the trends in atomic radius across a period. 5) Generally, as you go from left to right across a period on the periodic table, what happens to atomic radius? 6) Generally, as you go down a group in the periodic Atomi c Numbe r Eleme nt Symbo l Numbe r of Proto ns Number of Outer Electr ons Atomi c Radiu s 1 H 1 1 32 2 He 2 2 31 3 Li 3 1 123 4 Be 4 2 90 5 B 5 3 82 6 C 6 4 77 7 N 7 5 75 8 O 8 6 73 9 F 9 7 72 10 Ne 10 8 71 11 Na 11 1 154 12 Mg 12 2 136 13 Al 13 3 118 14 Si 14 4 111 15 P 15 5 106 16 S 16 6 102 17 Cl 17 7 99 18 Ar 18 8 98 19 K 19 1 203 20 Ca 20 2 174

Basic Trends Across the Periodic Table

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Page 1: Basic Trends Across the Periodic Table

Basic Trends Across the Periodic Table

1) Draw a line in the middle of a piece of graph paper, separating the page into top and bottom. On the top, plot a graph of number of outer electrons and, in the same coordinate system, a second graph of number of protons (y-axis) vs. atomic number (x-axis). On the bottom plot a separate graph of atomic radius vs. atomic number. For each graph connect successive dots with straight lines. Also, ensure that identical atomic numbers are plotted on the same vertical position on the sheet (i.e. atomic number 1 in the top graph should be on the same line as atomic number 1 in the bottom graph).

2) Examine your graph of electron number vs. atomic number.a) Which elements are found at the main

peaks on your graph (there should be 3)? What do these elements have in common?

b) Which elements are found at the main valleys on your graph (there should be 3)? What do these elements have in common?

3) Examine your graph of atomic radius versus atomic number.a) Which elements are found at the peaks on your graph? What do these elements

have in common?b) Which elements are found at the valleys on your graph? What do these

elements have in common?

4) How are proton number and atomic radii related (i.e. as the proton number increases, what happens to the atomic radius)? Use this to explain the trends in atomic radius across a period.

5) Generally, as you go from left to right across a period on the periodic table, what happens to atomic radius?

6) Generally, as you go down a group in the periodic table, what happens to atomic radius?

7) Why does radius increase as you go down a group?

Sum up your results to be able to present them to your classmates:

1. Going across a period, the atomic radius ___________________.

2. As you move from left to right across a period the number of

_________________ in the _______________ increases, so that there is an

__________________ in nuclear charge.

3. The added extra electrons go into the ________________ outer shell.

4. The increasing _______________ _________________ attracts the outer

electrons more strongly moving across the period, so ____________________

the atomic radius of the elements.

Atomic Number

Element Symbol

Number of

Protons

Number of Outer Electrons

Atomic Radius

1 H 1 1 32

2 He 2 2 31

3 Li 3 1 123

4 Be 4 2 90

5 B 5 3 82

6 C 6 4 77

7 N 7 5 75

8 O 8 6 73

9 F 9 7 72

10 Ne 10 8 71

11 Na 11 1 154

12 Mg 12 2 136

13 Al 13 3 118

14 Si 14 4 111

15 P 15 5 106

16 S 16 6 102

17 Cl 17 7 99

18 Ar 18 8 98

19 K 19 1 203

20 Ca 20 2 174

Page 2: Basic Trends Across the Periodic Table

Basic Trends Across the Periodic Table

1) Draw a line in the middle of a piece of graph paper, separating the page into top and bottom. On the top, plot a graph of number of outer electrons (y-axis) vs. atomic number (x-axis). On the bottom plot a separate graph of melting point vs. atomic number. For each graph connect successive dots with straight lines. Also, ensure that identical atomic numbers are plotted on the same vertical position on the sheet (i.e. atomic number 1 in the top graph should be on the same line as atomic number 1 in the bottom graph). In your graph, colour the dots for the metallic elements, the semi-metallic elements, and the non-metallic elements in different colours

2) Examine your graph of electron number vs. atomic number.a) Which elements are found at the main peaks on

your graph (there should be 3)? What do these elements have in common?

b) Which elements are found at the main valleys on your graph (there should be 3)? What do these elements have in common?

3) Examine your graph of melting points versus atomic number.a) Which elements are found at the peaks on your

graph? What do these elements have in common?

b) Which elements are found at the valleys on your graph? What do these elements have in common?

4) How are outer electron numbers, metallic character and melting points related (i.e. as the outer electron number increases in metals, what happens to the melting point)?

5) Generally, as you go from left to right across a period on the periodic table, what happens to the melting points?

6) Generally, as you go down a group in the periodic table, what happens to the melting points?

7) Which type of structures do you find as you go across the period? Use this to explain the trends in melting point across a period. Why do phosphorus and Sulphur not follow the trend of nitrogen and oxygen?

Sum up your results to be able to present them to your classmates:

1. Metallic properties ______________ as you move from left to right across the

period.

2. Melting points _____________ from sodium to aluminium because the number of

_________ _____________ increases and there are more delocalised electrons that

form a stronger metallic bond.

3. Metals are ______________ electrical conductors than non-metals.

4. The melting point of phosphorus is ______________ than sulphur’s melting point

because the molecules of phosphorus consist of __________ atoms than the

Atomic Number

Element Symbol

Number of Outer Electrons

Type of element

Melting point/

°C

1 H 1 non-metal

-259,14

2 He 2 non-metal -272

3 Li 1 metal 180,54

4 Be 2 metal 1278

5 B 3 non-metal 2300

6 C 4 non-metal 3500

7 N 5 non-metal -209,9

8 O 6 non-metal -218,4

9 F 7 non-metal

-219,62

10 Ne 8 non-metal -248,6

11 Na 1 metal 97,8

12 Mg 2 metal 650

13 Al 3 metal 660,37

14 Si 4 semi-metal 1410

15

P (molecules of 4 P atoms)

5 non-metal 44,1

16

S (molecules of 8 S atoms)

6 non-metal 112,8

17 Cl 7 non-metal

-100,98

18 Ar 8 non-metal -189

19 K 1 metal 63,65

20 Ca 2 metal 839

Page 3: Basic Trends Across the Periodic Table

sulphur molecules and thus have less van-der-Waals forces.

Atomic radii, numbers of protons and numbers of

electrons

1. Going across a period, the atomic radius ___________________.

2. As you move from left to right across a period the number of

_________________ in the _______________ increases, so that there is an

__________________ in nuclear charge.

3. The added extra electrons go into the ________________ outer shell.

4. The increasing _______________ _________________ attracts the outer

electrons more strongly moving across the period, so ____________________

the atomic radius of the elements.

Metallic properties, electric conductivity and melting

points

1. Metallic properties ______________ as you move from left to right across the

period.

2. Melting points _____________ from sodium to aluminium because the number of

_________ _____________ increases and there are more delocalised electrons that

form a stronger metallic bond.

3. Metals are ______________ electrical conductors than non-metals.

4. The melting point of phosphorus is ______________ than sulphur’s melting point

because the molecules of phosphorus consist of __________ atoms than the

sulphur molecules and thus have less van-der-Waals forces.