CBC Grade 9 Notes in Kenya-What is an atom?

An atom is the fundamental building block of all matter, representing the smallest unit of an element that retains its chemical properties. Atoms consist of a dense, positively charged nucleus (containing protons and neutrons) surrounded by a cloud of negatively charged electrons. Everything in the physical universe is made of atoms

CBC Grade 9 Notes in Kenya-What is an atom?

Key Characteristics and Structure:

• Nucleus: The center of the atom, containing protons (positive charge) and neutrons (neutral charge), which makes up nearly all the mass.
• Electrons: Negatively charged particles that orbit the nucleus in shells or energy levels.
• Balance: In a neutral atom, the number of protons equals the number of electrons.
• Size: Atoms are extremely small, generally around 0.1 nanometers in radius.
• Atomic Number: The number of protons determines the type of element (e.g., 1 proton = Hydrogen, 6 protons = Carbon).