What is an example of an atomic number practice problem?
The atomic number of an element is the number of protons in the nuclei of its atoms. In a neutral atom, the numbers of protons equals the number of electrons. Isotopes are atoms of the same element that have different numbers of neutrons in the nucleus, and therefore different mass numbers.The mass number of an isotope is the sum of the protons and neutrons in the nucleus. An example of an atomic number practice problem is:
The mass number of a neutral atom of an isotope of an element is 17, and the number of electrons is 8.
- What is the number of protons? Answer: In a neutral atom the number of protons and electrons are equal, so since this isotope of oxygen has 8 electrons, it also has 8 protons.
- What is its atomic number? Answer: The number of protons is the atomic number, so the atomic number is 8.
- What is the number of neutrons in the nucleus of the atom? Answer: Mass number is the sum of the protons and neutrons in the nucleus. Mass number minus the proton number equals the number of neutrons. 17 - 8 = 9 neutrons.
- What is the nuclear symbol for this element? Answer: From the periodic table we can see that this element is oxygen, having an atomic number of 8. The nuclear symbol includes the symbol of the element, and its mass number as a superscript in front of the symbol, and the atomic number as a subscript in front of the symbol. The nuclear symbol is