Fundamental Chemical Substances and Structures

Elements and Compounds

Elements are substances consisting of a single type of atom. Compounds are substances obtained by the grouping of atoms of different elements.

A Little History

Chemical Elements for Life: Bioelements

Bioelements are the chemical elements of living beings. The most abundant species are: C, H, O, N, Ca, P, Mg, S, Na, K, and Cl, and they make up more than 99% of these living things.

Trace Elements

Trace elements are present in lower proportions (approximately 0.1%) and are indispensable for all living things, such as Fe, Zn, Mn, F, I, Cu, and Co.

The RDA (Recommended Dietary Allowance) is the amount of nutrient that a healthy person should eat each day on average, as part of the diet, to maintain good health.

Isolated Atoms

The elements of Group 18, the noble gases, are presented as atmospheric gases at room temperature whose particles are isolated atoms. Their formulas coincide with the chemical symbol of each gas: He, Ne, Ar, Kr, Xe, and Rn.

Molecules

A molecule is a grouping of atoms that may belong to the same element or various different ones. It is the smallest part of a substance that retains its chemical properties. A molecular substance is the set of molecules.

Regarding Melting Point:

• Weak: The substance will be a gas.
• Strong: The substance will solidify.
• Intermediate: The substance will be liquid.

Crystals

A form of matter whose particles have a perfectly ordered internal structure that extends in three directions. Types:

• Ionic Crystal: Composed of ions: positive (cations) and negative (anions).
• Covalent Crystal: Crystal metal atoms: metal cation surrounded by a cloud of electrons.

The Most Common Chemical Compounds

• The carbon forms most of the compounds found in living things; for this reason, carbon compounds are called organic.
• The rest of the compounds are called inorganic because they are mainly found in the inanimate world, although some are also present in all living things, such as water, sodium chloride, etc.

Most Common Organic Compounds

These compounds are formed primarily by carbon and hydrogen. The part of chemistry that studies organic compounds is called organic chemistry. There are organic compounds formed by small molecules or very large molecules; they are called macromolecules, among them are proteins, fats, carbohydrates, and nucleic acids.

In function, not just the number of atoms that form their molecule acts, but how they are linked, and even how they are arranged in space. They are part of living beings, and if obtained artificially in a laboratory, they are called synthetic compounds.