Summary of atoms for BIOL121 - basic detail PDF

Preview

Summary

Summary for great understanding about atoms and they are used within the course. Basic summary for revision...

Description

ATOMS Atoms and elements

Atoms ➔ building blocks of all matter ➔ consist of three subatomic particles: ◆ protons, neutrons and electrons ➔ Protons (+ charge) and neutrons (no charge) are found in the nucleus of an atom ➔ Electrons (- charge) are found in energy levels called shells or orbits around the nucleus ➔ The charge on the proton and electron are the same size; because they have opposite charges they attract each other. ➔ Chemical reactions involve the rearrangement of electrons in the outermost shell Elements ➔ a substance made up of atoms with the same number of protons ➔ Simplest substances knowns (can be metals or non-metals) ➔ The periodic table shows elements arranged by their atomic number. The atomic number of an atom tells us how many protons it has in the nucleus ➔ Each element has its own name and chemical symbol, characteristic physical and chemical properties. Elements with similar properties are found in the same column of the periodic table.

Chemical symbols

➔ atoms of each element are represented by a chemical symbol ➔ consists of one or two dierent letters, but sometimes three letters are used for newly discovered elements ➔ Eg. N = Nitrogen atom

Atomic structure

Electronic structure

➔ electrons in an atom are arranged in energy levels, these are also calle shells or orbits ➔ Election atoms are found in the shell ➔ Innermost shell (lowest energy level) fills with elections ◆ Can only hold a 2 electrons till full and other 8+ ➔ Outermost shell (valence shell) occupied by valence electrons ◆ Valence electrons are the electrons of an atom that can participate in the formation of chemical bonds with other atoms...