Learn: Dot-and-Cross Diagrams (Ionic and Covalent)

Welcome!You've already learned about why atoms bond, including ionic and covalent bonding. Now, let's build on that knowledge by exploring dot-and-cross diagrams, a tool to visualise these types of bonding.

What are Dot-and-Cross Diagrams?Dot-and-cross diagrams are a way to represent how electrons are shared or transferred between atoms during bonding. They help us understand the arrangement of electrons in ionic and covalent compounds.

How Dot-and-Cross Diagrams WorkIn these diagrams, dots and crosses represent the electrons from different atoms. This helps us clearly distinguish which electrons belong to which atom. For ionic bonding, electrons are shown as transferred, while for covalent bonding, they are shared between atoms.

Dot-and-Cross Diagrams for Ionic BondingIn ionic bonding, electrons are transferred from one atom to another to achieve a stable electron arrangement. Dot-and-cross diagrams show which atom loses electrons and which atom gains them. The resulting ions are shown with their charges.

Example: Sodium ChlorideSodium (Na) loses one electron, forming a positive ion (Na⁺). Chlorine (Cl) gains that electron, forming a negative ion (Cl⁻). The dot-and-cross diagram shows sodium's electron as a cross and chlorine's electrons as dots. Each ion ends up with a full outer shell.

Dot-and-Cross Diagrams for Covalent BondingIn covalent bonding, electrons are shared between atoms to achieve a full outer shell. Dot-and-cross diagrams show the shared pairs of electrons between atoms, making it easy to visualise the bond.

Example: Water (H₂O)In a water molecule, oxygen shares one electron with each hydrogen atom to form covalent bonds. The dot-and-cross diagram shows each shared pair of electrons, with dots representing oxygen's electrons and crosses representing hydrogen's electrons.

Review Time!Great work! You've learned about how dot-and-cross diagrams represent ionic and covalent bonding. Let's test your understanding with a few questions.

Well Done!You've completed the lesson on dot-and-cross diagrams. Keep practising these concepts to master bonding types and how to visualise them!