Atomic Structure and Chemical Properties

Subatomic Particles of an Atom

Atoms are the basic units of matter, composed of three main subatomic particles:

• Protons: Positively charged particles located in the nucleus.

• Neutrons: Neutral particles also found in the nucleus.

• Electrons: Negatively charged particles that orbit the nucleus in electron shells.

Example: A carbon atom has 6 protons, 6 neutrons, and 6 electrons.

Atomic Number and Atomic Mass

• Atomic Number: The number of protons in the nucleus of an atom; determines the element's identity.

• Atomic Mass Number: The sum of protons and neutrons in the nucleus.

Formula:

Valence Electrons and Their Purpose

Valence electrons are the electrons in the outermost shell of an atom. They are crucial for chemical bonding and determine an atom's reactivity.

• Atoms with full valence shells are generally stable.

• Atoms with incomplete valence shells tend to form bonds to achieve stability.

Isotopes

Isotopes are atoms of the same element with different numbers of neutrons, resulting in different atomic mass numbers.

• Isotopes may be stable or unstable (radioactive).

• Example: Carbon-12 and Carbon-14 are isotopes of carbon.

Chemical Bonds and Molecules

Polar and Nonpolar Molecules

A polar molecule has an uneven distribution of charge due to differences in electronegativity between atoms, resulting in partial positive and negative ends.

• Example: Water (H2O) is a polar molecule.

• Nonpolar molecules have an even charge distribution.

Dehydration Synthesis Reaction

Dehydration synthesis is a chemical reaction where two molecules are joined by removing a water molecule.

• Common in the formation of macromolecules like proteins and carbohydrates.

Hydrogen Bonds in Water

Hydrogen bonds are weak attractions between the hydrogen atom of one molecule and an electronegative atom (like oxygen) of another molecule.

• Responsible for water's unique properties, such as high surface tension and boiling point.

Biochemistry: pH, Macromolecules, and Enzymes

pH Scale

The pH scale measures the concentration of hydrogen ions (H+) in a solution, indicating its acidity or alkalinity.

• Ranges from 0 (most acidic) to 14 (most basic).

• pH 7 is neutral.

Formula:

Triglycerides

Triglycerides are a type of lipid composed of one glycerol molecule and three fatty acids.

• Main form of stored energy in animals.

Saturated vs. Unsaturated Fats

• Saturated fats: Have no double bonds between carbon atoms; solid at room temperature.

• Unsaturated fats: Have one or more double bonds; liquid at room temperature.

Macromolecules: Carbohydrates, Proteins, Lipids

Macromolecules are large, complex molecules essential for life.

• Carbohydrates: Building blocks are monosaccharides (simple sugars).

• Proteins: Building blocks are amino acids.

• Lipids: Building blocks are fatty acids and glycerol.

Enzymes

Enzymes are biological catalysts that speed up chemical reactions without being consumed.

• Most enzymes are proteins.

• They lower the activation energy required for reactions.

Nucleic Acids and Genetic Information

Nucleotides and Nucleic Acids

Nucleotides are the building blocks of nucleic acids (DNA and RNA).

• Each nucleotide consists of a phosphate group, a sugar (deoxyribose or ribose), and a nitrogenous base.

DNA Base Pairing

In DNA, bases pair in a complementary fashion:

• Adenine (A) pairs with Thymine (T)

• Guanine (G) pairs with Cytosine (C)

Other Key Concepts

Organic vs. Inorganic Compounds

• Organic compounds: Contain carbon and hydrogen; typically found in living organisms.

• Inorganic compounds: Do not contain both carbon and hydrogen.

Vitamins Produced in the Skin

• Vitamin D is produced in the skin upon exposure to sunlight (UV radiation).

Location of Electrons and Protons in an Atom

• Protons: Located in the nucleus.

• Electrons: Located in electron shells surrounding the nucleus.

Summary Table: Macromolecule Building Blocks

Additional info: Some explanations and examples have been expanded for academic completeness and clarity.