Nuclear model of the atom
What is the nuclear model of the atom?
The model states that the atom consists of a dense positive center called the nucleus and is orbited by negatively charged electrons.
The nuclear model of the atom was first proposed by New Zealand scientist Ernest Rutherford while working in England under J. J. Thomson.
Scientists have shown that the atom consists of three sub atomic particles, the proton, the neutron and the electron.
- The center of an atom is called the nucleus. It contains most of the mass of an atom. Over 99.9% of the mass of an atom is found in its nucleus.
- The nucleus is composed of postively charged protons and neutrons which are neutral in charge.
- Negatively charged electrons orbit the nucleus at a great distance compared to the size of the nucleus.
- Most of the atom is consists of empty space.
Each sub atomic particle has its own unique characteristics and properties as shown by the table below.
|Sub atomic particle
||Relative mass||Function or role|
|Proton||In the nucleus||Positive (+)||1800||Determines the identity of an element. Each element has an unique number of protons called the Atomic Number.|
|Neutron||In the nucleus||Neutral (0)||1801||Helps stabilize the nucleus|
|Electron||Orbiting the nucleus||Negative (-)||1||Outer electrons involved in chemical reactions|
The nuclear model of the atom describes the atom as consisting of a positively charge dense nucleus made up of protons and neutrons. Negatively charged electrons orbit the nucleus at a great distance from the nuclues. Most of the atom is made up of empty space.
In an neutral atom the number of postively charged protons is equal to the number of negatively charged electrons. An atom of carbon has 6 protons and 6 electrons. An atom of bromine has 35 protons and 35 electrons.
- Name the three sub atomic particles that make up an atom.
- What is the center of an atom called?
- The nucleus of an atom is made of what two sub atomic particles?
- What are the respective charges of the proton and the neutron?
- What sub atomic particle orbits the nucleus of an atom?
- What is the charge of an electron?
- Describe the general structure of the nuclear model of the atom.
- What subatomic particle determines the identity of an element?
- What is the Atomic number of an element?
- What is the function or role of the neutron in an atom?
- What particle of the atom is involved in chemical reactions?
- An atom of oxygen has 8 protons. How many electrons does it have?