Atoms, elements and compounds

Topics

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Sample objectives

What this unit covers

• Elements, compounds and mixtures: Explain how elements, compounds, and mixtures differ from one another.
• Atomic structure and the Periodic Table: Explain the atom's structure, which consists of a central nucleus made up of neutrons and protons, with electrons arranged in shells around it.
• Atomic structure and the Periodic Table: Identify the relative charges and masses of protons, neutrons, and electrons.
• Ions and ionic bonds: Explain how positive ions, called cations, and negative ions, known as anions, are formed.
• Ions and ionic bonds: Identify that an ionic bond is a strong attraction due to electrostatic forces between ions with opposite charges.
• Simple molecules and covalent bonds: Explain that a covalent bond occurs when two atoms share a pair of electrons, resulting in electronic configurations similar to noble gases.
• Simple molecules and covalent bonds: Illustrate how covalent bonds are formed in simple molecules such as H₂, Cl₂, H₂O, CH₄, NH₃, and C₂H₄, using dot-and-cross diagrams to represent their electronic configurations.