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The number of protons in an atom is the atomic numberThe number of protons is equal to the atomic number of an atom. It is very important in knowing the number of electrons that surround the nucleus of an atom. In an atom, the electrical charge is neutral, due to the equal number of positive (protons) and negative (electrons) charges. The atomic number represents the protons in an atom and also identifies the element. Hydrogen has one proton. No other atom has just one proton. Heluim has two protons and no other element has only two protons. Lithium has three protons and so on.

The atomic number is equal to the number of protons in the nucleus, and for neutral atoms, it is the same as the number of electrons. In an attempt to keep atoms and ions from getting confused with one another, it is best to think of atoms as always being electrically neutral and ions should be considered charged positively or negatively depending on whether electrons are gained or lost by an atom during the chemical combination of atoms in forming substances such as water, salt and rust found on metals. Protons in atoms and ions are always the same for a specific atom.

Every element has a unique atomic number, and so each element's identity is determined by the number of protons in its nucleus.

However, the same element can have different numbers of neutrons in its nucleus. Two atoms of the same element with two different numbers of neutrons in the nucleus are called isotopes. Also, note that if an atom is not charged (neutral), then the number of protons must equal the number of electrons, and so the atomic number is also equal to the number of electrons in a neutral atom of each element.

However, if the atom is charged (and therefore called an ion), it will have a different number of electrons orbiting it. If the number of electrons is less than the number of protons, it will be a positively charged ion, and the charge will equal the difference between the number of electrons and protons. The same is true if it has more electrons than protons, except now the charge will be negative.

Look under the Web Links below this answer for a Periodic Table. The number listed for each element is its atomic number. Also see the Related Questions links for more information about the number of protons, neutrons, and electrons in an atom.

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Q: What is the atomic number and what does it tell you about the number of protons in an atom?
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What two things does the atomic number of an atom tell you?

The atomic number of an atom indicates the number of protons and identifies the element. In a neutral atom, it is also the number of electrons.

What does the atomic number tell you about the elements in the periodic table?

The atomic number represents the number of protons. The atomic mass represents the number of protons + neutrons.

What does an element's atomic number tell us?

An elements atomic number is the amount of protons and electrons in the nucleus of the atom. It also tells us the number of the element on the periodic table of elements.

How do you find the number of protons neutrons and electrons in an element?

When elements are written out, they are likely to be written as, for example, 2He4. The subscript 2 represents the number of protons in the element helium, which is its atomic number. In a periodic table of elements, finding the atomic number of an element will tell you how many protons it has. In a stable atom, the amount of electrons will always match the number of protons because the atom must be neutral. In helium, the two protons are balanced with two electrons. What follows won't help answer your question, but may help you better understand the atomic model. The superscript 4 is known as the atomic mass number of this particular element. In any element, it is the atomic mass number that describes how many protons and neutrons are present in an atom. We know that there are two protons in helium because of its atomic number, so it can be inferred that the two remaining particles are neutrons.

What does the atomic number of an element tell us?

the number of protons in an atoms nucleus

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