Fundamental Chemical & Biological Concepts

Elemental Properties & Periodic Trends

Metallic Properties in the Periodic Table

Across a Period

Within the same period, the metallic properties of elements increase as one moves to the left and decrease as one moves towards the right.

Down a Group

Within the same group, the metallic properties of elements increase as one moves down the table and decrease as one moves up.

Essential Elements & Their Occurrence

Bioelements: Building Blocks of Life

Primary Bioelements

These are the most abundant elements in living organisms:

• Hydrogen (H)
• Carbon (C)
• Nitrogen (N)
• Oxygen (O)
• Phosphorus (P)
• Sulfur (S)

Indispensable Secondary Bioelements

These are essential for life, required in smaller amounts:

• Sodium (Na)
• Magnesium (Mg)
• Potassium (K)
• Calcium (Ca)
• Manganese (Mn)
• Iron (Fe)
• Copper (Cu)
• Boron (B)
• Silicon (Si)
• Fluorine (F)
• Chlorine (Cl)
• Iodine (I)

Variable Secondary Bioelements

These elements are found in some organisms and may be essential for specific functions:

• Vanadium (V)
• Chromium (Cr)
• Molybdenum (Mo)
• Cobalt (Co)
• Nickel (Ni)
• Zinc (Zn)
• Bromine (Br)

Elements in Various Environments

Universal Elements

The most abundant elements in the universe are hydrogen and helium, along with other trace elements.

Atmospheric Elements

Key elements and compounds found in Earth's atmosphere include:

• Nitrogen (N)
• Oxygen (O)
• Carbon Monoxide (CO)
• Water Vapor
• Other gases

Earth's Crust Elements

Major elements composing the Earth's crust are:

• Oxygen (O)
• Silicon (Si)
• Aluminum (Al)
• Iron (Fe)
• Calcium (Ca)
• Sodium (Na)
• Potassium (K)
• Magnesium (Mg)
• Other elements

Molecular Structures & Material Characteristics

Diatomic Molecules Defined

Molecules consisting of two atoms are called diatomic.

Carbon Allotropes: Diamond & Graphite

Diamond Properties

Diamond is an allotrope of carbon. Its carbon atoms are arranged in a rigid, three-dimensional network. Diamond is renowned as one of the hardest known materials and possesses a very high melting point.

Graphite Properties

Graphite is another natural allotrope of carbon. It is a shiny black substance, soft and greasy to the touch, occurring in flakes or sheets that are slightly adherent and slide over each other.

Material Properties Overview

Properties of Metals

Most metals exhibit the following properties:

• Very hard
• Ductile (can be drawn into wires)
• Malleable (can be hammered into thin sheets)
• Good conductors of electrical current

Properties of Ionic Crystals

Ionic crystals typically have:

• High boiling and melting points
• No electrical conductivity in solid state
• Electrical conductivity when melted (molten)
• Good solubility in water, with aqueous solutions conducting electricity

Key Mineral Functions in the Human Body

Iron (Fe)

Iron participates in the uptake of oxygen (O₂) in the lungs and its transport throughout the body. It is found in meats, vegetables, bread, and egg yolk. Daily consumption of less than 10mg of iron can lead to pallor, apathy, and fatigue.

Calcium (Ca)

Calcium is a major component of bones and is involved in nerve conduction, muscle contraction, blood clotting, and hormone secretion and regulation. Good sources include beans, fish, and citrus. Deficiency can lead to neurological disorders such as dementia and depression.

Phosphorus (P)

Phosphorus is united with calcium in bones. It is found in dairy products, legumes, and nuts. Deficiency can contribute to renal failure.

Zinc (Zn)

Zinc is found in bone and muscle tissues, skin, liver, pancreas, prostate, retina, and blood. Sources include cereal flours and bread. Deficiency can cause anorexia, nausea, vomiting, and weakness.

Sodium (Na) and Potassium (K)

Sodium and potassium are the main inorganic constituents of body fluids. Distributed through food, potassium (K) is primarily located in the water inside the cells (intracellular fluid), while sodium (Na) is found in the water outside the cells (extracellular fluid).