The number of electrons, protons, and neutrons in an atom can be determined using the atomic number and mass number of the atom, as well as the information provided in the periodic table.
The atomic number of an atom is equal to the number of protons it contains. For example, carbon has an atomic number of 6, which means it has six protons in its nucleus.
Electrons are negatively charged particles that orbit around the nucleus of an atom. In a neutral atom, the number of electrons is equal to the number of protons. So, for a neutral carbon atom (atomic number 6), it will also have six electrons.
To determine the number of neutrons, you need to know the mass number of the atom. The mass number is the sum of the protons and neutrons in the nucleus. It is typically represented as a superscript to the left of the symbol of the element. For example, the most common isotope of carbon, Carbon-12, has a mass number of 12. This means it has 6 protons and 6 neutrons (12 - 6 = 6).
However, not all atoms of the same element have the same number of neutrons. Atoms of the same element that have different numbers of neutrons are called isotopes. Isotopes have the same atomic number (same number of protons) but different mass numbers (different number of neutrons). For example, Carbon-14 is an isotope of carbon that has 6 protons and 8 neutrons.
To summarize:
- The atomic number tells you the number of protons in an atom.
- In a neutral atom, the number of electrons is equal to the number of protons.
- The mass number is the sum of protons and neutrons.
- The number of neutrons can be calculated by subtracting the number of protons (atomic number) from the mass number.
It's important to note that the atomic number and mass number are often listed in the periodic table for each element, which can help in determining the number of protons, electrons, and neutrons for a specific atom or isotope.