The letters cd on the periodic table refer to the element Cadmium, a soft, silvery metal used in batteries, pigments, and coatings. Understanding where cadmium sits in the periodic table helps clarify its chemical behavior and industrial roles.
Below is a snapshot of cadmium key data, atomic structure, and common specifications that support safer handling and regulatory compliance.
| Symbol | Cd | Category | Post-transition metal |
|---|---|---|---|
| Atomic number | 48 | Group | 12 |
| Standard atomic weight | 112.414 | Period | 5 |
| Electron configuration | [Kr] 4d10 5s2 | Density | 8.65 g/cm³ |
| Melting point | 321.07 °C | Boiling point | 767 °C |
| Common oxidation states | +2 | CAS number | 7440-43-9 |
Atomic structure and electron configuration of cadmium
Examining cadmium atomic structure reveals a filled 4d subshell and two electrons in the 5s orbital. This configuration explains its preference for the +2 oxidation state in most compounds.
Its full electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10, which aligns with its placement in period 5, group 12 of the periodic table.
Shielding and effective nuclear charge influence cadmium ionization energy and covalent character in bonding. These quantum mechanical details underpin its metallic luster and moderate reactivity.
Physical properties and industrial specifications
Cadmium presents as a soft, malleable metal with a silvery-white appearance that tarnishes in air. Typical industrial grades specify limits on impurities to control mechanical performance and corrosion resistance.
| Property | Metric | Unit | Typical range |
|---|---|---|---|
| Density | Mass | Volume | 8.65 |
| Electrical resistivity | At 20 °C | Ohm centimeter | 7.76 × 10−5 |
| Thermal conductivity | At 25 °C | Watt per meter-kelvin | 96.6 |
| Coefficient of expansion | From 20 to 100 °C | Per kelvin | 30.5 × 10−6 |
| Tensile strength | Annealed | MPa | 70–130 |
Chemical behavior and common compounds
In chemical reactions, cadmium readily loses two electrons to form Cd2+ ions, producing soluble salts in acidic media. Its compounds include cadmium oxide, cadmium sulfide, and cadmium plating baths.
Environmental chemistry highlights cadmium mobility in soils and its tendency to accumulate in food chains. Understanding these pathways is essential for regulatory assessments and risk management.
Industries mitigate cadmium hazards by substituting less toxic materials where possible and by implementing closed-loop recycling for batteries and pigments. Material safety data sheets detail exposure limits and handling protocols.
Applications and usage contexts
Historically, cadmium found use in nickel-cadmium batteries, pigments in plastics and ceramics, and as a corrosion-resistant coating. Its unique properties enabled miniaturization and long-life energy storage in demanding environments.
Modern regulations have reduced cadmium in consumer electronics and favor alternative chemistries where feasible. Specialized sectors still rely on cadmium telluride in thin-film photovoltaics and certain metallurgical additives.
Ongoing research focuses on safer encapsulation methods, recovery from end-of-life products, and substitution strategies that balance performance, cost, and environmental impact.
FAQ
Reader questions
What does the cd symbol represent on the periodic table?
The cd symbol represents the element Cadmium, a chemical element with atomic number 48 and the symbol Cd in the periodic table.
What is the atomic number and group of cadmium?
Cadmium has an atomic number of 48 and belongs to group 12 on the periodic table.
Why is cadmium classified as a post-transition metal?
Cadmium is classified as a post-transition metal because it exhibits relatively low melting and boiling points, softness, and reduced electrical conductivity compared to typical transition metals.
What are the main industrial uses of cadmium today?
Main industrial uses of cadmium include rechargeable nickel-cadmium batteries, pigments in plastics and ceramics, and thin-film photovoltaic cells.