Elements — Definition & Overview

Chemical Elements

A chemical element is a pure substance that is made of only one type of atom. Elements cannot be broken down into any simpler substance. Each element is unique, having their own properties and characteristics.

Only about two dozen of the known elements are found in living things. For example, carbon plays a major part in living things. It is even known as the "backbone of life".

Before we get into the details, let's review some terms. Protons and neutrons make up the nucleus of an atom. The proton is the positively charged particle in the nucleus. The neutron is the neutral particle in the nucleus. The electron is the negatively charged particle that orbits the nucleus.

The number of protons in the nucleus of an element is called the atomic number. The number of protons in an atom determines what element it is. If all of the atoms have only one proton each, then the element is hydrogen. Similarly, if the nucleus has 50 protons, then the element is tin. The number of neutrons in an atom doesn't change what element it is; only the number of protons matters.

The number of neutrons does influence the mass number, which is the sum of the protons and neutrons together.

Check this out.

It's a box.
Wait. It's actually how we organize each element. Think of it like a trading card.

• The number at the top of each box shows the atomic number for each element and the letter underneath it is the element's abbreviation.
• Each element is given an abbreviation, typically one or two letters long. The abbreviations usually make sense for the name of the element. Except this one. The abbreviation Hg, as shown above, is for mercury.
• Underneath the element's abbreviation is something called the atomic mass. It is the combined weight of the protons, neutrons, and electrons.

The Periodic Table of Elements, shown below, is an amazing resource for figuring out all things related to elements.

Each of the over 100 elements we know of has a specific spot on this table. The elements are organized by atomic number, which are aligned so that elements with similar properties are in the same column, called a group. The rows, or periods, are organized by increasing atomic number.

$$\color{#8925AE}{\text{Vocabulary Review:}}$$

$\color{#8925AE}{\text{Atom}}$ : The smallest particle of an element that has the properties of that element

$\color{#8925AE}{\text{Nucleus}}$ : The positively and neutrally charged subatomic particles, protons and neutrons, located in the center of the atom

$\color{#8925AE}{\text{Electron}}$ : The mind-bogglingly small, negatively charged subatomic particles that orbit the nucleus

$\color{#8925AE}{\text{Proton}}$ : A positively charged subatomic particle located in the nucleus

$\color{#8925AE}{\text{Neutron}}$ : A subatomic particle with no charge located in the nucleus

$\color{#8925AE}{\text{Element}}$ : A substance that can not be broken down into other substances. All atoms of an element have the same atomic numbers

$\color{#8925AE}{\text{Atomic Number}}$ : The number of protons in the nucleus, which lets us identify which element it is

(Video) Understanding Atoms, Elements, and Molecules

by moviestar226

This video by moviestar226 is a great summary of atoms, elements, molecules, and chemical compounds.

The Periodic Table of Elements

An element is an atom or group of atoms that has a specific number of protons in its nucleus. Think of elements as pure. Each element only contains one kind of atom. Everything in the Periodic Table is an example of an element. (Its full name is the Periodic Table of the Elements.)

Examples of basic elements include gold, phosphorus, and carbon.

• The element gold is only made up of gold atoms. Every single gold atom has 79 protons.
• The element phosphorus is only made up of phosphorus atoms. Every single phosphorus atom has 15 protons.
• The element carbon is only made up of carbon atoms. Every single carbon atom has six protons.

See the pattern? An element is made up of only one type of atom, and all of those atoms have the same number of protons.

The number of protons in an atom affects the properties of an element, where it is in the periodic table, and what atomic number it has. An atomic number is the number of protons in each atom of an element.

(Video) The Genius of Mendeleev's Periodic Table

by Lou Serico on TED-Ed

This video explains how to understand the periodic table, which is an amazing resource and work of genius. It was created by Dmitri Mendeleev, who predicted chemical properties of elements, some of which wouldn't be discovered until one hundred years later.

He might be proud to know that scientists are still working hard to discover the missing elements. For example, tennessine (element 117) was only recently discovered in 2010.