Metals, Nonmetals, and Metalloids: Key Properties
Isotopes and element identity
- Protons define the element; a neutral element has the same number of electrons as protons.
- Neutrons vary among isotopes; periodic table does not show all isotopes.
- Isotopes share protons but differ in neutrons; transition properties can be less predictable across isotopes.
- Generally solid at room temperature (Mercury is the notable exception); high melting points.
- Excellent conductors due to free electrons moving between atoms (free electron model).
- Malleable and ductile; shiny (lustrous) because electrons reflect light.
- Tend to lose electrons to form positive ions.
- Many gases at room temperature; some liquids and solids.
- Generally poor conductors; solids are often brittle.
- Electrons tend to stay on atoms or in covalent bonds; form molecules.
- Tend to gain or share electrons rather than lose them.
- In-between metals and nonmetals in properties.
- Solid at room temperature; brittle.
- Semiconductors: conductivity between metals and nonmetals.
- Often shiny like metals but not as malleable or ductile.
How to use these properties
- Identify metal/nonmetal/metalloid from periodic table position to predict basic properties (physical and chemical).
- Physical properties: shape/size, melting point, boiling point, hardness, conductivity.
- Chemical properties: reactivity, corrosion resistance, acidity/basicity, bonding tendencies.
Real-world implications
- Materials selection based on composition and properties for applications (e.g., implants).
- For implants: mechanical strength, corrosion resistance, biocompatibility, and magnetic behavior (relevance to MRI/NMR safety).
Summary for quick recall
- Metals: lose electrons, conduct electricity, typically solid and hard, malleable, shiny.
- Nonmetals: gain/share electrons, poor conductors, varied states, often brittle.
- Metalloids: intermediate conductivity, brittle, semiconductors, shiny.
- Electron behavior largely explains these trends and helps predict properties of elements and compounds.
Next steps in course
- Thursday: ionic, covalent, and metallic compounds; properties of compounds.
- Next week: general properties of solids, liquids, and gases; group presentations on elements.