Simple Guide to IGCSE Edexcel Chemistry Principles

Welcome to our exploration of atomic structure, the foundation of chemistry!At the heart of every atom is a nucleus containing protons and neutrons, surrounded by electrons in shells.The atomic number of an element is equal to its number of protons, while the mass number is the sum of protons and neutrons.Electrons orbit the nucleus in shells, with each shell having a maximum capacity. The first shell can hold 2 electrons, the second 8, and the third 18.Elements in the periodic table are arranged by their atomic number and electron configuration. The rows are called periods, and the columns are called groups.Let's look at lithium's electron configuration. It has two electrons in its first shell and one in its second shell.Elements in the same group have similar properties. For example, Group 1 elements, the alkali metals, all have one outer electron and are highly reactive.An element's reactivity depends on its outer electrons, their distance from the nucleus, and the overall electron configuration.Now that we understand atomic structure, we're ready to explore how atoms combine through chemical bonding.In ionic bonding, electrons are transferred from one atom to another.Here, sodium gives up its outer electron to chlorine.These charged ions arrange themselves into a crystal lattice structure.Ionic compounds have distinct properties due to their strong electrostatic attractions.In covalent bonding, atoms share electrons instead of transferring them.In water, each hydrogen atom shares its electron with oxygen, forming covalent bonds.Covalent compounds have different properties from ionic compounds due to their shared electrons.In metallic bonding, positive metal ions are surrounded by a sea of delocalized electrons.The sea of mobile electrons gives metals their characteristic properties.These free electrons can move throughout the metal, allowing it to conduct electricity and heat.When balancing chemical equations, we ensure equal numbers of each element on both sides.The law of conservation of mass states that mass cannot be created or destroyed in a chemical reaction.Let's explore how to calculate the number of moles using mass and molar mass.For solutions, concentration is calculated by dividing moles by volume in liters.For gases, we use the ideal gas equation to calculate volume under specific conditions.Percentage yield compares the actual amount of product obtained to the theoretical maximum.To find the empirical formula, we convert masses to moles and find the simplest whole number ratio.Let's review some common mistakes to avoid in chemical calculations.Let's review the key points to remember for successful chemical calculations.Thanks for learning about chemical calculations with Spark.E!