Element
Definition and meaning of Element in chemistry.
An element is a pure substance consisting of only one type of atom, defined by its unique number of protons (atomic number), that cannot be broken down into simpler substances by ordinary chemical means.
In more detail
Every atom of a given element has the same atomic number (proton count), though atoms of the same element can differ in neutron number, giving rise to isotopes. Elements are the fundamental building blocks of matter and combine chemically in fixed ratios to form compounds. Currently 118 elements are known, organized in the periodic table by increasing atomic number and recurring patterns of chemical behavior; 94 occur naturally on Earth, while the rest have been synthesized artificially.
Key facts
| Field | General Chemistry |
|---|---|
| Defining property | Atomic number (number of protons) |
| Known elements | 118 (94 naturally occurring) |
| Symbol example | Fe (iron), atomic number 26 |
Oxygen (O) is an element with atomic number 8, meaning every oxygen atom has 8 protons; it exists naturally as the diatomic molecule O2 and cannot be decomposed into simpler substances chemically.
Frequently asked questions
How is an element different from a compound?
An element consists of only one type of atom, while a compound consists of two or more different elements chemically bonded together in a fixed ratio, such as water (H2O).
Can an element be broken down further?
Not by chemical reactions. However, nuclear reactions can change one element into another by altering the number of protons in the nucleus, as in radioactive decay or nuclear fission.