-
The correct answer is c: The element has 12 protons and has 28 neutrons.
- Explanation: The atomic number (12) indicates the number of protons in the element. The mass number (40) represents the total number of protons and neutrons. To find the number of neutrons, you subtract the number of protons from the mass number: 40 - 12 = 28 neutrons.
-
The correct answer is b: The number of protons and electrons must be the same.
- Explanation: For an atom to be considered neutral, it must have an equal number of protons (positively charged) and electrons (negatively charged), thus cancelling each other's charge.
-
The correct answer is a: Number of electrons in the valence shell.
- Explanation: Elements in the same group (column) of the periodic table have similar chemical properties because they have the same number of electrons in their outermost shell (valence shell).
A student looks up an element on the periodic table. The table says that the atomic number of the element is 12 and the mass number of the element is 40. What information do these two numbers convey about the element?
a
The element has 40 protons and 12 neutrons
b
The element has 12 protons and 12 neutrons
c
The element has 12 protons and has 28 neutrons
d
The element has 28 protons and 40 neutrons
2. In order for an atom to be considered "neutral", which of the following must be true?
a
The number of protons and neutrons must be the same
b
The number of protons and electrons must be the same
c
There are more protons than electrons
d
There are more neutrons than protons
3. In all elements in a group, the thing that is the same is the:
a
Number of electrons in the valence shell
b
Number of electrons
c
Number of protons
d
Number of neutrons
1 answer