Atoms, Protons, Neutrons, and Electrons: Basic Atomic Structure

Atoms and Elements

Subatomic Particles

Atoms are the fundamental building blocks of matter, composed of three main subatomic particles: protons, neutrons, and electrons. Understanding their arrangement and properties is essential for studying chemistry.

• Proton (p+): A positively charged particle found in the nucleus of an atom. The number of protons determines the atomic number and the identity of the element.

• Neutron (n0): A neutral particle also located in the nucleus. Neutrons contribute to the mass of the atom but do not affect its charge.

• Electron (e-): A negatively charged particle that orbits the nucleus in electron shells. Electrons are involved in chemical bonding and reactions.

Determining Subatomic Particle Numbers

To describe an atom fully, it is important to know the number of protons, neutrons, and electrons it contains. These can be determined using the atomic number and mass number.

• Atomic Number (Z): The number of protons in the nucleus. It defines the element.

• Mass Number (A): The total number of protons and neutrons in the nucleus.

• Number of Neutrons: Calculated by subtracting the atomic number from the mass number.

Formulas:

• Number of Neutrons: $\text{Neutrons} = \text{Mass Number} - \text{Atomic Number}$

• Number of Protons: $\text{Protons} = \text{Atomic Number}$

• Number of Electrons (for a neutral atom): $\text{Electrons} = \text{Atomic Number}$

Example Calculation

• Given: An atom with a mass number of 23 and an atomic number of 11 (Sodium, Na).

• Number of Protons: 11

• Number of Neutrons: $23 - 11 = 12$

• Number of Electrons (neutral atom): 11

Summary Table: Subatomic Particles

Particle	Symbol	Charge	Location	Relative Mass
Proton	p+	+1	Nucleus	1
Neutron	n0	0	Nucleus	1
Electron	e-	-1	Outside nucleus (electron cloud)	~0 (1/1836 of proton)

Additional info: The notes referenced 'Kromic x' and 'Module Seven', which may refer to a specific example or module in a course. The core content here is expanded to cover the basic structure of atoms, as relevant to GOB Chemistry Chapter 4: Atoms and Elements.