Learn: Atomic Structure

Welcome!Welcome to today's lesson on atomic structure. This is a key concept in chemistry, as it helps us understand the building blocks of matter. Let's explore what atoms are made up of and how this knowledge is used!

What is an atom?An atom is the smallest unit of matter that retains the properties of an element. It consists of three main subatomic particles: protons, neutrons, and electrons. Understanding the structure of atoms helps us explain chemical reactions and the properties of materials.

Subatomic particlesAtoms are made up of protons (positively charged), neutrons (no charge), and electrons (negatively charged). Protons and neutrons are found in the nucleus (centre of the atom), while electrons orbit around the nucleus.

Structure of the AtomMost of the mass of an atom is concentrated in its nucleus, which contains protons and neutrons. The electrons orbit the nucleus in shells, which are regions at fixed distances from the nucleus. The number of protons determines the element's atomic number.

What are isotopes?An isotope is a variation of an element that has the same number of protons but a different number of neutrons. This means isotopes of the same element have the same atomic number but different mass numbers. For example, carbon has isotopes like carbon-12 and carbon-14.

Atomic number and mass numberThe atomic number is the number of protons in an atom and determines the type of element. The mass number is the total number of protons and neutrons in the nucleus. For example, helium has an atomic number of 2 and a mass number of 4.

Electron arrangementElectrons are arranged in shells around the nucleus. The first shell can hold up to 2 electrons, the second up to 8, and so on. The arrangement of electrons in shells determines the chemical properties of an element.

Electronic ConfigurationThe electronic configuration shows how electrons are arranged in an atom. For example, sodium (Na) has 11 electrons, so its configuration is 2, 8, 1. This indicates 2 electrons in the first shell, 8 in the second, and 1 in the third.

Review Time!Great work! You've learnt about atomic structure, including atoms, subatomic particles, isotopes, and electron arrangements. Now let's test your understanding with a few questions.

ConclusionWell done! You've learned about the key concepts of atomic structure. These ideas will help you understand the properties of elements and their behaviour in chemical reactions.