Revision Of Atomic Structure & Bonding

Atomic Structure

Fundamental Particles

• Atoms consist of three main particles: protons, neutrons, and electrons. Protons are positively charged, neutrons are neutral, and electrons are negatively charged.

• The nucleus of an atom contains protons and neutrons, while electrons orbit around the nucleus in electron shells.

• The atomic number of an element is defined by the number of protons in its nucleus, which also determines the element's identity. For example, boron has an atomic number of 5, indicating it has 5 protons.

Charge and Stability

• Atoms are neutral because they have an equal number of protons and electrons, resulting in zero overall charge.

• Ions are charged particles that form when atoms gain or lose electrons to achieve stability, often following the octet rule.

• The charge of an ion indicates the number of electrons lost or gained; for example, Na+ indicates that sodium has lost one electron.

Periodic Table Organization

• The periodic table is organized into columns (groups) and rows (periods). Groups share similar chemical properties due to having the same number of valence electrons.

• Group 1 elements, such as sodium (Na), have one electron in their outer shell, making them highly reactive and likely to form +1 ions.

• Periods indicate the number of electron shells; for instance, elements in period 1 have one electron shell.

Ionic Bonding

Ionic Compounds

• Ionic compounds are formed when atoms transfer electrons, resulting in the formation of positive and negative ions that attract each other due to electrostatic forces.

• The formula for an ionic compound, such as Na₂O, indicates the ratio of ions present; in this case, two sodium ions bond with one oxide ion.

• The stability of ionic compounds arises from the strong ionic bonds formed between oppositely charged ions.

Bonding Arms and Charges

• The concept of 'bonding arms' refers to the number of electrons an atom can lose or gain to form stable ions.

• The charge on an ion reflects the number of bonding arms; for example, Na+ has one bonding arm because it has lost one electron.

• Understanding the charge of ions is crucial for predicting how they will combine to form compounds.

Electron Movement

• Electrons can move between different atoms, allowing for the formation of bonds and the creation of compounds.

• This movement is essential in chemical reactions, where atoms rearrange to form new substances.

• The ability of electrons to be shared or transferred is fundamental to both ionic and covalent bonding.