1c And 1d Atomic Structure And The Periodic Table

Question 1

What are the 3 sub-atomic particles in an atom?

Answer 1

Electron, neutron and proton

Question 2

What is in the middle of the atom?

Answer 2

The nucleus

Question 3

What is the nucleus made out of?

Answer 3

Protons and neutrons.

Question 4

What sub-atomic particle orbit the nucleus? And is inside the shells that surround the nucleus?

Answer 4

Electrons

Question 5

What is the mass and charge of the sub-atomic particle, proton?

Answer 5

Teh mass of teh sub-atomic particle, proton is 1 and the charge of the sub-atomic particle, proton is +1(positive)

Question 6

What is the charge and the mass of the sub-atomic particle, neutron?

Answer 6

The charge of the sub-atomic particle, neutron is = (neutral) and the mass of the sub-atomic particle, neutron is 1

Question 7

What is the charge and mass of the sub-atomic particle, electron?

Answer 7

The mass of the sub-atomic particle, electron is 0 or 1/1836. The charge of the sub-atomic particle, electron is -1(negative)

Question 8

Why does an atom need to have the same number of proton and electrons need to be the same number?

Answer 8

It is so that the charge of an atom would be neutral because atoms need to have an overall charge of 0.

Question 9

How do find out the number of protons?

Answer 9

By looking at the atomic number

Question 10

How do you find out the number of electrons?

Answer 10

By looking at the atomic number

Question 11

How do you find the number of neutrons?

Answer 11

By subtracting the mass number by the atomic number

Question 12

What is an isotope?

Answer 12

Isotopes are different forms of a chemical element, with the same number of protons, but different numbers of neutrons.

Question 13

What makes an atom of silver different from an atom of potassium?

Answer 13

Different number of protons, electron and neutron

Question 14

Why do we not measure the mass of atoms using a standard unit of mass? E.g. grams?

Answer 14

Because it if far too small.

Question 15

Chlorine-35 and chlorine-37 are two isotopes of the element chlorine. What are the similarities
and differences between their nuclei? -you need numbers.

Answer 15

They have the same number of protons =17 but they have a different number of neutrons. Chlorine 35=18 and chlorine-37 =20

Question 16

Why would it not be useful to refer to the atomic number when describing the difference between two isotopes?

Answer 16

Because the atomic numbers would be the same so if you just refer to them as atomic numbers they would be just the same element.

Question 17

Relative Atomic Mass (Ar)
Relative atomic mass of an element is the average mass of its atoms compared to 1/12th of the mass of a
carbon-12 atom.
Although as the smallest atom, it might appear easier to use hydrogen as the standard we compare it to, carbon-12 is used as it is the only element with an exact whole number mass (12.000). On more detailed periodic tables hydrogen-1 (as there are other isotopes) has an exact Ar of 1.008.
On your periodic table, most relative atomic masses have been rounded to whole numbers. However, you may notice a few that are not. This is due to isotopes.
Calculating Relative Atomic Mass
Relative atomic mass is actually the average of all of the different isotopes of an element. It is weighted so that it takes into account the abundance (how much there is) of each isotope.
Example:
Letsʼ look at an imaginary element X. There are two isotopes of X, one with a mass of 10 and one with a mass of 12.
If we were to simply calculate the average, then we would find: 10+12 =11
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2
However, this is not thinking about whether there is more of one isotope than the other. For element X, there are 5 atoms of 10X for every 1 atom of 12X.
So if we were to calculate a more accurate average, then we would calculate:

10+10+10+10+10+12 =10.33
______________________
6
This is a more accurate way of calculating Ar as it takes into account how many atoms of each isotope there are.
However when we are dealing with real atoms and isotopes, we do not have small numbers of atoms which we can just use to calculate the average. We would usually get told the percentage of each isotope. For example, in a sample of chlorine gas, 75% is chlorine-35 and 25% is chlorine-37. The actual Ar of chlorine is 35.5, which suggests that there is more chlorine-35 than chlorine-37.

We need to use a special formula to calculate the Ar. Ar=(mass1x%1)+(mass2x%2)……
Note the % must be expressed in decimal form. E.g. 72% would be 0.72. If you forget to put it in the decimal form, you can divide by 100 at the end.

Worked Example
Given that the abundance of 35Cl is 75% and 37Cl is 25%, prove that the relative atomic mass of chlorine is 35.5.
First we need to write out the formula. As we only have two isotopes, we only need to write out two brackets.
Ar=(mass1x%1)+(mass2x%2)
Now put in the masses of the two isotopes
Ar=(35x%1)+(37x%2)
Now put in the percentage abundances, remembering to convert them to decimals. Ar=(35x0.75)+(37x0.25)
Type the calculation into a scientific calculator, remembering to be careful about placing the brackets. Ar = 35.5.

Question 18

There are three naturally occurring isotopes of argon. They are argon-36, argon-38 and argon-40.
The calculated Ar of argon is 39.9. Which of the isotopes do you think is most abundant?

Answer 18

Argon-40,
because 39.9 is closer to 40. Because the mass number is closest
to the relative mass number

Question 19

Copper exists as a mixture of two isotopes. Copper-63 is 69.17% abundant and has a mass of 62.9296. Copper-65 is 30.83% abundant and has a mass of 64.9278. Calculate the atomic mass of copper.

Answer 19

63.5456

Question 20

Galium has two naturally occurring isotopes. The mass of galium-69 is 68.9256 and it is 60.108% abundant. The mass of galium-71 is 70.9247 and it is 39.892% abundant. Calculate the relative atomic mass of galium.

Answer 20

69.7231

Question 21

Bromine has two naturally occurring isotopes. Bromine-79 has a mass of 79.918 and is 50.69% abundant. Given that the atomic mass of bromine is 79.904, work out the abundance of bromine-81, the other isotope of bromine.

Answer 21

49.31%

Question 22

Use your knowledge of isotope to explain why the ice cubes are sinking in the glass of water.

Answer 22

The formula of water is H2O. The hydrogen in the ice cubes is an isotope called hydrogen-2. This has 1 proton, 1 neutron and 1 electron, compared to the hydrogen-1 which has 1 proton, no neutrons and one electron. Because hydrogen-2 is more dense, the ice cubes will sink in the water.

Question 23

What is the difference between the elements on the periodic table?

Answer 23

Different numbers of protons, electrons and neutrons.

Question 24

How many electrons can the first shell hold?

Answer 24

2 elctrons

Question 25

How many electrons can the second shell hold?

Answer 25

8 electrons

Question 26

How many electrons can the 3rd shell hold?

Answer 26

8 electrons

Question 27

How many electrons can the fourth shell hold?

Answer 27

8 electrons

Question 28

What properties of copper mean that it can be used in electrical wires.

Answer 28

Ductility

Question 29

Why is a mixture of copper and tin used to make church bells?

Answer 29

They are sonorous

Question 30

What is malleability?

Answer 30

capability of being shaped or extended by hammering, forging, etc.