Unit 1.2 - Chemistry in Living Systems
Part 1 - Intro to Biochemistry
Chemistry Intro
- The scientific study of the properties of matter, the composition of matter, and the ways in which different substances will react.
- An ATOM is the smallest basic unit of matter.
- EVERYTHING is made of atoms.
- The word atom comes from the Greek word “atomos,” meaning “unable to be cut.”
Chemistry Intro
Elements
- A chemical element is a pure substance that consists entirely of one type of atoms
- The periodic table arranges all known elements into predictable patterns of characteristics
Elements
Subatomic Particles
- Atoms have 2 regions: nucleus and electron cloud
- The nucleus is made up of protons and neutrons
- The electron cloud is filled with electrons
Protons
- Protons have a positive (+) charge
- The number of protons determines what the atom is
- Ex: All atoms with 6 protons are Carbon atoms
- Call this the Atomic Number
- Looking at the periodic table, this is the number above the element’s name
Protons
Neutrons
- Neutrons have no charge (electrically neutral)
- Roughly the same size as a proton
- To determine the number of neutrons an atom has, we subtract the number of protons from the atomic mass (the number at the bottom of each square on the periodic table)
Isotopes
- The number of protons can never change in an element, but the number of neutrons can change
Isotopes
Electrons
- Super small particles (much smaller than protons) move and flow around the nucleus
- Mass is so small, it is negligible
- Electrons have a negative (-) charge
Electrons
Ions
- Neutral atoms have an equal number of protons and electrons
- Sometimes, atoms can gain/lose electrons
- Cations (positive ions) have an overall positive charge
- If there are more protons than electrons
- Anions (negative ions) have an overall negative charge
- There are more electrons than protons
Compounds
- Compounds are formed when elements combine with other elements.
- We can show the atoms contained in a compound and their proportions with a chemical formula.
- Ex. Water H2O and Table salt NaCl
- The physical and chemical properties of a compound are very different from those of the elements they contain.
Compounds
Ionic Bonds
- Formed when one or more electrons are transferred from one atom to another.
- Atoms with a positive charge have lost electrons
- Atoms with a negative charge have gained electrons
Covalent Bonds
- Forms when electrons are shared between atoms
- When atoms share 2 electrons, they form a single bond
- When atoms share 4 electrons, they form a double bond
- Structure that forms as a result is called a molecule (smallest unit of a most compounds)
Van der Waals Forces
- Atoms in a molecule do not always share the electrons in covalent bonds evenly.
- Intermolecular forces of attraction, or in other words, attractions between partial negative and partial positive charges are called Van der Waals forces.
- Van der Waals forces are not as strong as covalent bonds or ionic bonds, but they can hold molecules together.
Additional Resources
Science in Pajamas
Other Videos
Science in Pajamas
Atomic Structure
Ions and Isotopes
Chemical Bonding
Bohr's Model
Physical and Chemical Changes
Chemical and Physical Changes
Other Videos
RicochetScience - Structure of an Atom
Science Geeks - Atomic Structure: Atoms, Ions, and Isotopes
RicochetScience - Chemical Bonding: Ionic vs Covalent
Socratica - 4 Types of Chemical Bonds in Biology
Bozeman Science - The Bohr Atom
Spot Channel - Chemical and Physical Changes
RS - Structure of an Atom
SG - Atomic Structure: Atoms, Ions, and Isotopes
RS - Chemical Bonding: Ionic vs Covalent
S - 4 Types of Chemical Bonds in Biology
SC - Chemical and Physical Changes