Basics of Chemistry

Chemistry

- a science that deals with the composition, structure, and properties of substances and with the transformations that they undergo;
- the composition and chemical properties of a substance;
- chemical processes and phenomena (as of an organism);
- a strong mutual attraction, attachment, or sympathy between two people

Element

- are chemically the simplest substance and hence cannot be broken down using chemical reactions;
- is a substance whose atoms all have the same number of protons: another way of saying this is that all of a particular element's atoms have the same atomic number;

atom

• the basic unit of a chemical element;

• is made up of three particles: protons, neutrons and electrons;

• consists of a nucleus of positively-charged protons and electrically neutral neutrons with negatively-charged electrons orbiting this nucleus.

Electron

• negatively charged particle of an atom;

• it spreads out about the nucleus at somedistance from it;

Proton

• is a subatomic particle found in the nucleus of every atom;

• The number of proton in the nucleus is the defining defining property property of an element, element, and is referred referred toas the atomic number.

Neutron

• electrically neutral particle having a massslightly greater than that of proton;

• located in a small region at the center of the atom, called the nucleus

Atomic number (Z)

is the number of protons in the nucleus of each atom of an element.

Mass number (A)

is the total number of neutrons and protons present in the nucleus of an atom of an element.

Isotopes

atoms that have the same atomic number but different mass numbers.