GCSE Year 11 –Physics (Unit 4)
Atomic Structure and Radioactivity
1. Atoms and Elements:
Atoms are the basic units of matter, consisting of a nucleus composed of protons and
neutrons, surrounded by a cloud of electrons.
Elements are substances made up of only one type of atom. They are represented by
chemical symbols (e.g., H for hydrogen, O for oxygen) and are organized on the
periodic table. Each element has a unique atomic number, which corresponds to the
number of protons in the nucleus. For example, Carbon has an atomic number of 6,
meaning it have six protons.
2. Subatomic Particles:
a) Protons are positively charged particles found in the nucleus of an atom. They
contribute to the atomic mass and determine the element's identity.
, b) Neutrons are neutral particles also located in the nucleus. They add to the mass of the
atom without affecting its charge.
c) Electrons are negatively charged particles that orbit the nucleus in specific energy
levels or shells. They are much smaller than protons and neutrons and contribute
negligible mass to the atom.
3. Atomic Number and Mass Number:
a) The atomic number of an element is the number of protons in the nucleus. It
uniquely identifies the element and determines its chemical properties.
b) The mass number of an atom is the sum of its protons and neutrons. It gives an
approximation of the atom's mass.
Atomic Structure and Radioactivity
1. Atoms and Elements:
Atoms are the basic units of matter, consisting of a nucleus composed of protons and
neutrons, surrounded by a cloud of electrons.
Elements are substances made up of only one type of atom. They are represented by
chemical symbols (e.g., H for hydrogen, O for oxygen) and are organized on the
periodic table. Each element has a unique atomic number, which corresponds to the
number of protons in the nucleus. For example, Carbon has an atomic number of 6,
meaning it have six protons.
2. Subatomic Particles:
a) Protons are positively charged particles found in the nucleus of an atom. They
contribute to the atomic mass and determine the element's identity.
, b) Neutrons are neutral particles also located in the nucleus. They add to the mass of the
atom without affecting its charge.
c) Electrons are negatively charged particles that orbit the nucleus in specific energy
levels or shells. They are much smaller than protons and neutrons and contribute
negligible mass to the atom.
3. Atomic Number and Mass Number:
a) The atomic number of an element is the number of protons in the nucleus. It
uniquely identifies the element and determines its chemical properties.
b) The mass number of an atom is the sum of its protons and neutrons. It gives an
approximation of the atom's mass.
