1. Atoms Of The Same Element But Different Masses
2. Atoms Of The Same Element Can Have Different Properties

1. 12) Atoms of the same element with different mass numbers are called A) ions B) neutrons C) allotropes D) chemical families E) isotopes. Answer ( 13) The current model of the atom in which essentially all of an atom's mass is contained in a very small nucleus, whereas most of an atom's volume is due to the space in which the atom's electrons move was established by A) Dalton's Atomic Theory C.
2. Atoms of the same element always have different atomic weights. Atoms of the same element can have neutrons but exist without protons. If an oxygen atom has 8 protons in its nucleus, what is its atomic number? If a substance cannot be broken down chemically into a simpler substance, it is.
3. Isotopes are atoms of the same element (that is, with the same number of protons in their atomic nucleus), but having different numbers of neutrons. Thus, for example, there are three main isotopes of carbon. All carbon atoms have 6 protons in the nucleus, but they can have either 6, 7, or 8 neutrons.

Many people might think atoms and elements are the same. However, atoms and elements do have a few differences when you start breaking it down. The main difference is elements are made of atoms. Learn other differences between atoms and elements by dissecting these two terms. Explore examples of elements and atoms.

What Is an Atom?

Atom, smallest unit into which matter can be divided without the release of electrically charged particles. It also is the smallest unit of matter that has the characteristic properties of a chemical element. As such, the atom is the basic building block of.

You might have heard the term atom thrown around in chemistry. And, there's a good reason for that; it’s extremely important. Every compound, molecule, or element you come across will be made of atoms. For example, humans are made of atoms. Air is made of atoms. Your computer… made of atoms. Everything is made of atoms.

This is why you can’t begin to understand the difference between atoms and elements without first understanding what an atom is and what it’s made of. Simply put, atoms are the building blocks of elements. They are some of the smallest bits of what you would call ordinary matter.

Structure of an Atom

Like everything else, atoms have a few different things floating around inside of them. These subatomic particles include:

• neutrons - with no charge
• protons - positively charged
• electrons - negatively charged

The protons and neutrons are in the atomic nucleus of the atom, while the electrons orbit the atomic nucleus. Think of this as similar to the way the planets all orbit the sun. That’s an atom in a nutshell. Well, if a nutshell was orbited by lots of little electrons, that is.

What Is an Element?

With atoms out of the way, it’s time to look at elements. If you’ve ever seen a Periodic Table of Elements, then you probably have some idea of what elements are. But to break it down into a simple definition, elements are all the different types of atoms we know exist on Earth. They are arranged by their atomic number on the Periodic Table of Elements.

For example, gold is an element. If you were to hold a chunk of pure gold in your hand, you would be holding an element. Other elements include:

• Hydrogen
• Boron
• Carbon
• Neon
• Magnesium
• Silicon
• Aluminum
• Chloride
• Oxygen
• Calcium

Elements and Atomic Number

What makes something an element is the fact that all the atoms have the same number of protons in the nucleus. While you can find them all on the periodic table, let’s look at the common elements’ mercury and copper.

• Mercury is an element with 80 protons in its nucleus. It has an atomic number of 80.
• Copper is made of atoms with 29 protons in the nucleus. Therefore, it has an atomic number of 29.

What Is the Difference Between an Element and a Molecule?

With atoms and elements all cleared up, it’s important to understand the difference between a molecule and an element. Because like all things in the world, elements and molecules are both made of atoms. You know elements are all the different types of atoms on the periodic table. Molecules are what you get when those atoms are combined. Unlike elements, molecules can be made from the same or different elements. The key to a molecule is that two or more atoms are bonded together.

For example, water is a molecule made of hydrogen and oxygen. It’s actually made of two hydrogen atoms and one oxygen atom. You can also have molecules of a single atom bonded together like two oxygen atoms. This makes up the oxygen humans breathe.

Difference Between Atoms and Elements

It can be easy to see why elements and atoms get confused because elements are atoms. They are just a group of all the same kind of atoms. All the known elements on Earth can be found in the periodic table of elements.

Science is fun right? Telegram parse_mode markdown example. Keep the chemistry fun going by exploring the difference between atoms and molecules. You can also have more chemistry fun by reading up on molecules and compounds.

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Learning Objectives

• Define and differentiate between the atomic number and the mass number of an element.
• Explain how isotopes differ from one another.

Now that we know how atoms are generally constructed, what do atoms of any particular element look like? How many protons, neutrons, and electrons are in a specific kind of atom? First, if an atom is electrically neutral overall, then the number of protons equals the number of electrons. Because these particles have the same but opposite charges, equal numbers cancel out, producing a neutral atom.

Atomic Number

In the 1910s, experiments with x-rays led to this useful conclusion: the magnitude of the positive charge in the nucleus of every atom of a particular element is the same. In other words, all atoms of the same element have the same number of protons. Furthermore, different elements have a different number of protons in their nuclei, so the number of protons in the nucleus of an atom is characteristic of a particular element. This discovery was so important to our understanding of atoms that the number of protons in the nucleus of an atom is called the atomic number (Z).

For example, hydrogen has the atomic number 1; all hydrogen atoms have 1 proton in their nuclei. Helium has the atomic number 2; all helium atoms have 2 protons in their nuclei. There is no such thing as a hydrogen atom with 2 protons in its nucleus; a nucleus with 2 protons would be a helium atom. The atomic number defines an element. Table (PageIndex{1}) lists some common elements and their atomic numbers. Based on its atomic number, you can determine the number of protons in the nucleus of an atom. The largest atoms have over 100 protons in their nuclei.

Example (PageIndex{1})

What is the number of protons in the nucleus of each element?

1. aluminum
2. iron
3. carbon

According to Table 2.4.1, aluminum has an atomic number of 13. Therefore, every aluminum atom has 13 protons in its nucleus.

Iron has an atomic number of 26. Therefore, every iron atom has 26 protons in its nucleus.

Carbon has an atomic number of 6. Therefore, every carbon atom has 6 protons in its nucleus.

Exercise (PageIndex{1})

What is the number of protons in the nucleus of each element? Use Table 2.4.1.

1. sodium
2. oxygen
3. chlorine

Sodium has 11 protons in its nucleus.

Oxygen has 8 protons in its nucleus.

Chlorine has 17 protons in its nucleus

How many electrons are in an atom? Previously we said that for an electrically neutral atom, the number of electrons equals the number of protons, so the total opposite charges cancel. Thus, the atomic number of an element also gives the number of electrons in an atom of that element. (Later we will find that some elements may gain or lose electrons from their atoms, so those atoms will no longer be electrically neutral. Thus we will need a way to differentiate the number of electrons for those elements.)

Example (PageIndex{2})

How many electrons are present in the atoms of each element?

1. sulfur
2. tungsten
3. argon

The atomic number of sulfur is 16. Therefore, in a neutral atom of sulfur, there are 16 electrons.

The atomic number of tungsten is 74. Therefore, in a neutral atom of tungsten, there are 74 electrons.

The atomic number of argon is 18. Therefore, in a neutral atom of argon, there are 18 electrons.

Exercise (PageIndex{2})

How many electrons are present in the atoms of each element?

1. magnesium
2. potassium
3. iodine

Mg has 12 electrons.

K has 19 electrons.

I has 53 electrons.

Isotopes

How many neutrons are in atoms of a particular element? At first it was thought that the number of neutrons in a nucleus was also characteristic of an element. However, it was found that atoms of the same element can have different numbers of neutrons. Atoms of the same element (i.e., same atomic number, Z) that have different numbers of neutrons are called isotopes. For example, 99% of the carbon atoms on Earth have 6 neutrons and 6 protons in their nuclei; about 1% of the carbon atoms have 7 neutrons in their nuclei. Naturally occurring carbon on Earth, therefore, is actually a mixture of isotopes, albeit a mixture that is 99% carbon with 6 neutrons in each nucleus.

An important series of isotopes is found with hydrogen atoms. Most hydrogen atoms have a nucleus with only a single proton. About 1 in 10,000 hydrogen nuclei, however, also has a neutron; this particular isotope is called deuterium. An extremely rare hydrogen isotope, tritium, has 1 proton and 2 neutrons in its nucleus. Figure (PageIndex{1}) compares the three isotopes of hydrogen.

The discovery of isotopes required a minor change in Dalton’s atomic theory. Dalton thought that all atoms of the same element were exactly the same.

Most elements exist as mixtures of isotopes. In fact, there are currently over 3,500 isotopes known for all the elements. When scientists discuss individual isotopes, they need an efficient way to specify the number of neutrons in any particular nucleus. The mass number (A) of an atom is the sum of the numbers of protons and neutrons in the nucleus. Given the mass number for a nucleus (and knowing the atomic number of that particular atom), you can determine the number of neutrons by subtracting the atomic number from the mass number.

A simple way of indicating the mass number of a particular isotope is to list it as a superscript on the left side of an element’s symbol. Atomic numbers are often listed as a subscript on the left side of an element’s symbol. Thus, we might see

[mathrm{^{mass: numberxrightarrow{hspace{45px}} 56}_{atomic: number xrightarrow{hspace{35px}} 26}Fe} label{Eq1}]

which indicates a particular isotope of iron. The 26 is the atomic number (which is the same for all iron atoms), while the 56 is the mass number of the isotope. To determine the number of neutrons in this isotope, we subtract 26 from 56: 56 − 26 = 30, so there are 30 neutrons in this atom.

Example (PageIndex{3})

How many protons and neutrons are in each atom?

1. (mathrm{^{35}_{17}Cl})
2. (mathrm{^{127}_{53}I})

In (mathrm{^{35}_{17}Cl}) there are 17 protons, and 35 − 17 = 18 neutrons in each nucleus.

Pa drivers license test questionsdownload free apps. In (mathrm{^{127}_{53}I}) there are 53 protons, and 127 − 53 = 74 neutrons in each nucleus.

Exercise (PageIndex{3})

How many protons and neutrons are in each atom?

1. (mathrm{^{197}_{79}Au})
2. (mathrm{^{23}_{11}Na})

In (mathrm{^{197}_{79}Au}) there are 79 protons, and 197 − 79 = 118 neutrons in each nucleus.

Atoms Of The Same Element But Different Masses

In (mathrm{^{23}_{11}Na}) there are 11 protons, and 23 − 11 = 12 neutrons in each nucleus.

It is not absolutely necessary to indicate the atomic number as a subscript because each element has its own unique atomic number. Many isotopes are indicated with a superscript only, such as ¹³C or ²³⁵U. You may also see isotopes represented in print as, for example, carbon-13 or uranium-235.

Summary

The atom consists of discrete particles that govern its chemical and physical behavior. Each atom of an element contains the same number of protons, which is the atomic number (Z). Neutral atoms have the same number of electrons and protons. Atoms of an element that contain different numbers of neutrons are called isotopes. Each isotope of a given element has the same atomic number but a different mass number (A), which is the sum of the numbers of protons and neutrons.

Almost all of the mass of an atom is from the total protons and neutrons contained within a tiny (and therefore very dense) nucleus. The majority of the volume of an atom is the surrounding space in which the electrons reside. A representation of a carbon-12 atom is shown below in Figure (PageIndex{2}).

Concept Review Exercises

1. Why is the atomic number so important to the identity of an atom?
2. What is the relationship between the number of protons and the number of electrons in an atom?
3. How do isotopes of an element differ from each other?
4. What is the mass number of an element?

Answers

1. The atomic number defines the identity of an element. It describes the number of protons in the nucleus.
2. In an electrically neutral atom, the number of protons equals the number of electrons.
3. Isotopes of an element have the same number of protons but have different numbers of neutrons in their nuclei.
4. The mass number is the sum of the numbers of protons and neutrons in the nucleus of an atom.

Key Takeaways

• Each element is identified by its atomic number. The atomic number provides the element's location on the periodic table
• The isotopes of an element have different masses and are identified by their mass numbers.

Contributors and Attributions

Atoms Of The Same Element Can Have Different Properties

• Anonymous