Home Page Textbooks Nelson Science Perspectives 10 Section 5-4: Patterns and the Periodic Table

Nelson Science Perspectives 10

1st Edition

Christy C. Hayhoe, Doug Hayhoe, Jeff Major, Maurice DiGiuseppe

ISBN: 9780176355289

Textbook solutions

All Solutions

Section 5-4: Patterns and the Periodic Table

Exercise 1

Solution 1

Solution 2

Step 1

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The data that allows us to know the number of electrons in an atom is the number of protons in the nucleus of the atom, specifically the atomic number of the chemical element in the periodic table.

Result

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The data that allows us to know the number of electrons in an atom is the number of protons in the nucleus of the atom.

Step 1

1 of 1

The group number of an atom in the periodic table is equal to the number of its valence electrons, while the period number indicates the number of orbits/or shells used for electronic configuration in the pattern $2,8,8,…$. These 2 pieces of information can be used to predict the number of electrons in an atom. For example, Potassium lies in group 1 therefore it can be concluded that it has 1 valence electron. Its period number is 4. This implies that its electronic configuration is $2,8,8,1$ and therefore it has a total of $2+8+8+1=19$ electrons.

Exercise 2

Step 1

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State at room temperature:

Metals:
All metals are solid at room temperature. The only exception is mercury which is a liquid.

Non-Metals:

All non-metals are either liquids or gases at room temperature. The only exception is carbon which is a solid.

Step 2

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Electrical conductivity:

Metals:

All metals are good conductors of electricity.

Non-metals:

All non-metals are bad conductors of electricity. The only exception is graphite(carbon) which is an electrical conductor.

Step 3

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Lustre:

Metals:
All metals have a shiny appearance.

Non-Metals:

All non-metals have a dull appearance.

Step 4

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Number of valence electrons:

Metals:
All metals have either 1, 2 or 3 electrons in their outermost orbit.

Non-Metals:

All non-metals have 4 or more electrons in their outermost orbit.

Result

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Click to see answers.

Exercise 3

Step 1

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Halogens are group VII elements. The halogen in the second period is Flourine.

Step 2

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Alkaline earth metals are group II elements. The alkaline earth metal in the fifth period is Stronium.

Step 3

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The noble gas with the smallest atomic number is Helium with an atomic number of 2.

Step 4

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The non-metal in the fifth period with seven outer most electrons must lie in group VII and is Iodine.

Step 5

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Alkali metals are group I elements. The alkali metal in the fourth period is Potassium.

Step 6

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The metal in the third period with three outer most electrons must lie in group III and is Aluminium.

Step 7

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The unreactive gas of the second period is the nobel gas Neon in group VIII.

Result

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Click to see answers$.$

Exercise 4

Step 1

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Nitrogen – $14$: Note that there are $7$ protons and $14-7=7$ neutrons in the nucleus of the atom and 7 electrons revolving around it.

Exercise scan

Step 2

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Aluminum – $27$: Note that there are $13$ protons and $27-13=14$ neutrons in the nucleus of the atom and 13 electrons revolving around it.

Exercise scan

Step 3

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Chlorine – $35$: Note that there are $17$ protons and $35-17=18$ neutrons in the nucleus of the atom and 17 electrons revolving around it.

Exercise scan

Step 4

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Magnesium – $24$: Note that there are $12$ protons and $12-12=12$ neutrons in the nucleus of the atom and 12 electrons revolving around it.

Exercise scan

Step 5

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Disclaimer:
Note that the sizes of the electrons shown here vary. This is because the diagrams are not drawn to scale.

Result

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Click to see diagrams.

Exercise 5

Step 1

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a.
Study the Periodic Table. The element having the atomic number 118 lies in group VIII. This implies that an element with an atomic number of 119 will lie in the next group after group VIII and since group VIII is the last of the $8$ groups, the new element must lie in group I. This element will therefore be a member of the family of alkali metals.

Step 2

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Since it is established that this element will lie in group I, it can be further concluded that it will have $1$ electron in its outermost shell

Step 3

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The new element lies in group I of the Periodic table, it can be deduced that it will have properties similar to that of alkali metals. A physical property of this element will be that it will be soft in texture. It will react violently with water to form its metallic hydroxide and release hydrogen gas according to the equation:

$$
mathrm{2X_{(s)} + 2H_2O_{(l)} longrightarrow 2XOH_{(aq)} + H_2{(g)}}
$$

, where X is the symbol of the new element.

Result

4 of 4

Click to see answers.

Exercise 6

Step 1

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i is a nonmetal, ii is a metal, iii is a nonmetal, iv is a metal.

Step 2

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iv is a metal that is liquid at standard temperature and pressure

Step 3

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The metals are likely to conduct electricity because of their metallic bonds containing mobile electrons

Result

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i is a nonmetal, ii is a metal, iii is a nonmetal, iv is a metal.

Exercise 7

Step 1

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a. The number of outermost electrons within a period increment by $1$, as we move horizontally from left to right across the Periodic table. For example, in period 2, we have Lithium with an outermost electron of 1, followed by Beryllium with 2 outermost electrons, followed by Boron with 3 outermost electrons and so on.

Step 2

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b. The number of outermost electrons within a group remain constant, as we move vertically from top to bottom. This is the reason why group number represents the number of outermost electrons of its elements.

Exercise 8

Step 1

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Atoms are electrically neutral because the number of negatively charged electrons in them are equal to the number of positively charged protons within their nucleus.

Result

2 of 2

Number of protons and electrons is always equal.

Exercise 9

Step 1

1 of 2

Potassium is a highly reactive metal. It can react violently with atmospheric moisture to form potassium hydroxide and hydrogen gas.

$$
mathrm{K_{(s)} + H_2O_{(g)} longrightarrow KOH_{(aq)} + H_2{(g)}}\
$$

The hydrogen gas formed is also very combustible. Because of this property of potassium, it is stored under paraffin oil.

Result

2 of 2

Potassium is a highly reactive metal. It can react violently with atmospheric moisture to form potassium hydroxide and hydrogen gas.

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Section 5-4: Patterns and the Periodic Table

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