Intro to Chemistry

• Matter is anything that takes up space and has mass.
• Atoms are the smallest chemical units of matter.

Atomic Structure

• Electrons are negatively charged subatomic particles circling a nucleus.
• The nucleus contains neutrons and protons.
• Neutrons are uncharged particles within the nucleus.
• Protons are positively charged particles within the nucleus.
• An element is composed of a single type of atom.
• The atomic number is equal to the number of protons in the nucleus.
• Atomic mass (atomic weight) equals the sum of the masses of protons, neutrons, and electrons.

Isotopes

• Isotopes are atoms of a given element that differ in the number of neutrons in their nuclei.

Electron Configurations

• Only the electrons of atoms interact, so electrons determine an atom's chemical behavior.
• Electrons occupy electron shells.
• Valence electrons are electrons in the outermost shell that interact with other atoms.

Common Elements of Life

• Hydrogen (H) has an atomic number of 1, an atomic mass of 1 dalton, and is a component of organic molecules and water, releasing H+ by acids.
• Boron (B) has an atomic number of 5, an atomic mass of 11 daltons, and is essential for plant growth.
• Carbon (C) has an atomic number of 6, an atomic mass of 12 daltons, and is the backbone of organic molecules.
• Nitrogen (N) has an atomic number of 7, an atomic mass of 14 daltons, and is a component of amino acids, proteins, and nucleic acids.
• Oxygen (O) has an atomic number of 8, an atomic mass of 16 daltons, and is a component of many organic molecules and water, releasing OH- by bases and necessary for aerobic metabolism.
• Sodium (Na) has an atomic number of 11, an atomic mass of 23 daltons, and is the principal cation outside cells.
• Magnesium (Mg) has an atomic number of 12, an atomic mass of 24 daltons, and is a component of many energy-transferring enzymes.
• Silicon (Si) has an atomic number of 14, an atomic mass of 28 daltons, and is a component of the cell wall of diatoms.
• Phosphorus (P) has an atomic number of 15, an atomic mass of 31 daltons, and is a component of nucleic acids and ATP.
• Sulfur (S) has an atomic number of 16, an atomic mass of 32 daltons, and is a component of proteins.
• Chlorine (Cl) has an atomic number of 17, an atomic mass of 35 daltons, and is the principal anion outside cells.
• Potassium (K) has an atomic number of 19, an atomic mass of 39 daltons, and is the principal cation inside cells; essential for nerve impulses.
• Calcium (Ca) has an atomic number of 20, an atomic mass of 40 daltons, and is utilized in many intercellular signaling processes; essential for muscular contraction.
• Manganese (Mn) has an atomic number of 25, an atomic mass of 54 daltons, and is a component of some enzymes and acts as an intracellular antioxidant; used in photosynthesis.
• Iron (Fe) has an atomic number of 26, an atomic mass of 56 daltons, and is a component of energy-transferring proteins and transports oxygen in the blood of many animals.
• Cobalt (Co) has an atomic number of 27, an atomic mass of 59 daltons, and is a component of vitamin B12.
• Copper (Cu) has an atomic number of 29, an atomic mass of 64 daltons, and is a component of some enzymes; used in photosynthesis.
• Zinc (Zn) has an atomic number of 30, an atomic mass of 65 daltons, and is a component of some enzymes.
• Molybdenum (Mo) has an atomic number of 42, an atomic mass of 96 daltons, and is a component of some enzymes.
• Iodine (I) has an atomic number of 53, an atomic mass of 127 daltons, and is a component of many brown and red algae.

Answer to Active Exercise

• Oxygen has 8 protons.

Chemical Bonds

• Chemical bonds are formed when atoms combine by sharing or transferring valence electrons.
• A molecule is composed of two ore more atoms held together by chemical bonds.
• A compound is a molecule composed of more than one element.
• A covalent bond involves the sharing of a pair of electrons by two atoms.
• Electronegativity is the attraction of an atom for electrons.
• The pull its nucleus exerts on electrons is greater in more electronegative atoms.

Nonpolar Covalent Bonds

• Shared electrons spend equal amounts of time around each nucleus.
• Atoms have similar electronegativities.
• No poles exist.
• Carbon atoms form four nonpolar covalent bonds with other atoms.
• Organic compounds contain carbon and hydrogen atoms, with an electronegativity difference of less than 0.4.

Polar Covalent Bonds

• Unequal sharing of electrons due to significantly different electronegativities.
• Most important polar covalent bonds involve hydrogen.
• Allows for hydrogen bonding.
• The electronegativity difference is 0.4-1.8.

Ionic Bonds

• Ionic bonds occur between two atoms with vastly different electronegativities.
• Atoms have either positive (cation) or negative (anion) charges.
• Cations and anions attract each other and form ionic bonds where no electrons are shared.
• Ionic bonds typically form crystalline ionic compounds known as salts.
• Electronegativity difference is > 1.8.

Hydrogen Bonds

• Electrical attraction between partially charged H+ and full or partial negative charge on same or different molecule.
• Hydrogen bonds are weaker than covalent bonds but essential for life.
• Help to stabilize 3-D shapes of large molecules.

Table 2.2 Characteristics of Chemical Bonds

• Nonpolar covalent bonds have pairs of electrons that are nearly equally shared between two atoms.
• Polar covalent has electrons that spend more time around the more electronegative of two atoms.
• Ionic bods happen when electrons are stripped from a cation by an anion.
• Hydrogen bonds have partial positive charges on hydrogen atoms being attracted to full and partial negative charges on other molecules or other regions of the same molecule.
• Nonpolar and polar covalent bonds are strong while hydrogen and ionic bonds are weak.

Chemical Reactions

• The making or breaking of chemical bonds.
• Involve reactants and products.
• Biochemistry involves chemical reactions of living things.

Synthesis Reactions

• Synthesis Reactions involve the formation of larger, more complex molecules
• They require energy (endothermic)
• A common type of synthesis reaction is dehydration synthesis.
• A water molecule is formed during dehydration synthesis.
• All the synthesis reactions in an organism are called anabolism.

Decomposition Reactions

• Decomposition Reactions break bonds within larger molecules to form smaller atoms, ions, and molecules.
• They release energy (exothermic).
• A common type is hydrolysis.
• Ionic components of water are added to products.
• All the decomposition reactions in an organism are called catabolism.

Water

• The most abundant substance in organisms
• Possesses many special characteristics due to its two polar covalent bonds: including
  • Cohesive molecules that generate surface tension
  • Being an excellent solvent
  • Remaining liquid across a wide range of temperatures.
  • Being able to absorb significant amounts of heat energy without changing temperature
  • Participating in many chemical reactions

Salts

• Compounds that dissociate in water into cations and anions other than H+ and OH-
• Cations and anions of salts are electrolytes:
  • Create electrical differences between inside and outside of cell
  • Transfer electrons from one location to another
  • Form important components of many enzymes

Functional Groups and Organic Macromolecules

• They contain carbon and hydrogen atoms
• Atoms often appear in arrangements called functional groups
• Macromolecule are large molecules used by all organisms
• The different types are Lipids, Carbohydrates, Proteins, and Nucleic acids
• Monomers are the basic building blocks of macromolecules

Lipids

• Lipids are all hydrophobic.
• There are four groups of lipids, including:
  • Fats (triglycerides)
  • Phospholipids
  • Waxes

Carbohydrates

• Carbohydrates serve as sources of energy.
• They help form the structural integrity of molecules and serve as recognition sites during intercellular interactions.
• Types of carbohydrates include:
  • Monosaccharides
  • Disaccharides
  • Polysaccharides

Proteins

• Proteins are composed mostly of carbon, hydrogen, oxygen, nitrogen, and sulfur.
• Their functions include:
  • Structure
  • Enzymatic catalysis
  • Regulation
  • Transportation
  • Defense and offense

Amino Acids

• The monomers that make up proteins
• Most organisms use only 21 amino acids in protein synthesis.
• Side groups affect how amino acids interact with one another and how a protein interacts with other molecules
• A covalent peptide bond is formed between amino acids.
• The building blocks for proteins

Nucleic Acids and Nucleotides

• Nucleic acids are Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
• They are the vital genetic material of cells and viruses.
• RNA also acts as enzyme, binds amino acids, and helps form polypeptides.
• Nucleotides have a nucleic acid function.
• DNA constitutes the genetic material of all organisms and of many viruses.
• Instructions for the synthesis of RNA and proteins is carried by nucleic acids.
• Synthesis of all molecules in an organism is controlled by nucleic acids.

This quiz covers the basics of chemistry, including the structure of atoms, chemical bonds, and chemical reactions. It also touches on the importance of water in living organisms. Test your knowledge of fundamental chemistry concepts.