The composition of matter is the stuff that makes up matter. At its most basic, matter is made up of atoms. Atoms are tiny. They are so tiny that you have about 100,000,000,000,000,000,000,000 atoms in your fingertip! One strand of your hair is about a million atoms wide.
Atoms
Atoms are mostly empty space. There is a small nucleus at the center of the atom. The nucleus is composed of protons and neutrons. Surrounding the nucleus are electrons. Our models show electrons are dots orbiting the nucleus, but they really form a cloud around the nucleus.
Protons and neutrons are made up of even smaller things. You can learn about all of the parts of atoms by checking out the presentation below. If you would like to purchase your own copy of the presentation, you can get it at Teachers Pay Teachers.
Elements
Atoms that have the same number of protons are called elements. For example, all of the atoms in carbon have 12 protons.
If the number of protons in an atom changes, the element changes. For example, the Sun is so hot that hydrogen atoms fuse together and become helium atoms. Hydrogen atoms have one protons and helium atoms have two protons. Radioactive elements, like uranium, lose protons. A uranium atom that loses two protons becomes a thorium atom.
The number of neutrons in an atom does not determine the element of the atom. Atoms from the same element can have different numbers of neutrons. Most of the time, an atom has the same number of protons and neutrons. However, sometimes there are a different number of neutrons. These atoms are called isotopes. Carbon-14 is a famous isotope. It has 14 neutrons instead of 12. Archaeologists use carbon-14 to determine how old artifacts are because it is radioactive, like uranium, and decays. Archeologists compare the amount of carbon-14 and carbon-12 in the artifact to determine its age.
There are currently 118 confirmed elements. Only 94 of these elements are found naturally on Earth. The rest have been made by scientists in laboratories. Scientists may be able to make new elements someday, or we may discover new elements.
Elements are organized using the periodic table. Dmitri Mendeleev published the periodic table in 1869. He didn't know about all of the elements we know about today, but he left spaces in his table where he predicted new elements. If you want to learn more about the periodic table, you can check out the presentation below. You can purchase your own copy of the presentation at Teachers Pay Teachers.
Molecules and Compounds
Molecules and compounds are made up of more than one atom.
Molecules can have atoms from the same element, such as oxygen gas made up of two oxygen atoms, or different elements, such as water made up of one oxygen atom and two hydrogen atoms.
Compounds must have atoms from different elements. For example, oxygen gas is not a compound, but water is.
All molecules are compounds, but not all compounds are molecules.
You can learn more about molecules and compounds by checking out the presentation below. You can also purchase the presentation at Teachers Pay Teachers.
Types of Bonds
Atoms in molecules and compounds are held together through bonds. There are different types of bonds that hold atoms together.
Ionic Bonds
Ionic bonds happen when electrons jump from one atom to another. To understand why electrons would jump from one atom to another, you need to understand how electrons are organized around an atom's nucleus. You can learn about these topics by checking out the presentation below.
Covalent Bonds
Covalent bonds happen when two or more atoms share electrons.
Covalent bonds start the same way ionic bonds start. Atoms do not have full outer shells. However, instead of one atom giving up an electron and the other atom taking the electron, in a covalent bond, both atoms use the electron or electrons to fill their outer shells.
Metallic Bonds
Metallic bonds are similar to covalent bonds because atoms are sharing electrons, but they are a little bit different. The electrons in a metallic bond are delocalized. That means they are shared by all of the atoms around them.
Delocalized electrons give metals their unique properties. Metals, such as copper, gold, silver, and iron, are all good conductors of electricity. They are also malleable, which means they can be flattened into sheets, and ductile, which means they can be stretched into wires. The delocalized electrons also make metals shiny and lustrous. In other words, they have smooth and reflective surfaces.
Hydrogen Bonds
Hydrogen bonds only happen between hydrogen and a highly electronegative atom, such as oxygen or nitrogen. Electronegative atoms pull really strongly on electrons. Hydrogen only has one electron, so the pull from these electronegative atoms holds the hydrogen to the other atom.
Hydrogen bonds are much weaker than ionic or covalent bonds, but this makes them very important in biological systems where things need to come together and pull apart regularly. For example, hydrogen bonds hold DNA strands together, but these strands need to come apart during DNA replication.
Electrons
As you can see from the section on bonding, electrons are a fascinating and important part of atoms. If you are interested in learning more about electrons, you can check out the presentation below. If you would like to purchase a copy of the presentation, you can do so at Teachers Pay Teachers.
You can get back to my Matter Homepage to check out more information and resources related to learning about matter!
Matter
Related Posts
