Complete the missing information in the chart. Assume these are neutral atoms.

Question

Element symbol __ Atomic number __ Mass number 40 Number of protons __ number of neutrons. __ number of electrons 20

Answer 1

To complete the missing information in the chart for an element with a mass number of 40, 20 protons, and 20 electrons, we can deduce the following:

1. Element symbol: The atomic number of an element is equal to the number of protons. Since there are 20 protons, the atomic number is 20. The element with atomic number 20 is Calcium, represented by the symbol Ca.

2. Atomic number: This is the same as the number of protons, which is 20.

3. Mass number: Given as 40.

4. Number of protons: This is 20 (as calculated directly from the atomic number).

5. Number of neutrons: The number of neutrons can be calculated using the formula:
   \[ \text{Number of Neutrons} = \text{Mass Number} - \text{Atomic Number} \] \[ \text{Number of Neutrons} = 40 - 20 = 20 \]

6. Number of electrons: Given as 20 (since it is a neutral atom).

Here's the completed chart:

| Element symbol | Atomic number | Mass number | Number of protons | Number of neutrons | Number of electrons | |----------------|---------------|-------------|--------------------|---------------------|----------------------| | Ca | 20 | 40 | 20 | 20 | 20 |

So the completed information is:

• Element symbol: Ca
• Atomic number: 20
• Mass number: 40
• Number of protons: 20
• Number of neutrons: 20
• Number of electrons: 20