2.1: Atoms and Molecules
Atoms and elements are the smallest structures in the universe. These substances cannot be broken down any further. Elements come together to form molecules which are the building blocks of the lowest level of life, the cell. To understand biology, you need to understand these foundation elements that form the structures of life.
The primary subatomic particles are protons, neutrons, and electrons. Protons and neutrons make up the nucleus of an atom. Electrons are found outside the nucleus. A proton has an electrical charge of +1. A neutron is nearly identical in size to a proton, but it has no charge. An electron is much smaller than a proton or neutron. An electron is also a charged particle. Despite being much smaller than a proton, the charge of an electron is equal in magnitude to the charge of a proton. However, the charge is opposite, so each electron has a charge of -1.
Watch this lecture, which introduces the atom and discusses the relationship between atoms and elements. What do you think the periodic table represents?
This video provides an engaging and thought-provoking introduction to the concept of atoms in chemistry, exploring their philosophical significance and the structure of atoms, including protons, neutrons, and electrons. It also touches upon the concept of atomic number and isotopes. Join us as we delve into the fascinating world of atoms!
Watch these short videos for an overview of the elements within an atom: protons, neutrons, and electrons. Make sure you understand the definitions for the proton, neutron, and electron. You should also be able to define atomic measurements, such as atomic number and mass, and calculate the number of subatomic particles based on this number.
Atoms have a specific structure that determines their behavior in an element or compound. Electrons occupy spaces around the nucleus. These spaces have a hierarchical arrangement. An orbital is a space that can be occupied by electrons. Each orbital can contain up to two electrons.
There are different types and shapes of orbitals: s, p, d, and f. There is only one kind of s orbital, but there are three kinds of p orbital, five d orbitals, and seven f orbitals. A collection of orbitals of the same type makes up a subshell, and a collection of subshells makes up a shell (also called an energy level). The first shell includes only one subshell (the s subshell), which is made up of only one s orbital. The second shell is made up of two subshells (an s and a p subshell), with the s subshell being made up of one s orbital and the p subshell being made up of three p orbitals. Since different shells contain different numbers of orbitals, each shell has a different maximum number of electrons it can hold.
Watch this lecture to learn about orbitals and review the structure of an atom.
Living structures are three-dimensional (3D), and electrons fly in three-dimensional orbitals. This feature is critical because it explains how elements join to form 3D molecules that build the 3D tissues and organs of life. Watch this lecture, which describes how the electrons fly in different orbitals.
Watch this lecture to learn about electron configuration and valence electrons.
Read this section, which describes how atoms and elements form different types of bonds between atoms.
After you read, see if you can answer these questions: What makes ionic bonds different from covalent bonds? Why are hydrogen bonds and van der Waals interactions necessary for cells? How do buffers help prevent drastic swings in pH? Why can some insects walk on water? What property of carbon makes it essential for organic life? Compare and contrast saturated and unsaturated triglycerides.
Watch this lecture to learn about the details of ionic, covalent, and metallic bonds, and how to balance chemical equations.
Now that you have learned about atoms and their structures, watch this overview of how to write and draw atoms, molecules, and chemicals correctly.
Now, let's learn how to balance chemical reactions. Elements come together to form molecules called products. It is important to make sure the same amount of elements are found on both sides of the chemical reaction.