The atomic number of titanium is 22. This metallic element is located in Group 4 of the periodic table and is known for its high strength, low density, and excellent corrosion resistance. Its remarkable properties make it highly valuable in various industries, including aerospace for aircraft and spacecraft components, medical for surgical implants, and everyday items like watches and sports equipment. Titanium's atomic number, which represents the number of protons in its nucleus, is crucial for understanding its chemical behavior and bonding characteristics. Its electron configuration leads to unique chemical and physical properties that differentiate it from other elements.

A Polyvinyl Chloride (PVC) Christmas tree is a synthetic alternative to traditional live trees, made from a type of plastic called PVC. This material is used to create the needles of the tree, offering a durable, fire-resistant, and easy-to-shape option for holiday decorations. These trees come in various sizes and styles, mimicking different types of real trees. PVC Christmas trees are popular due to their convenience, cost-effectiveness, and long-term usability, reducing the need for annual tree purchases and minimizing environmental concerns associated with tree cutting. However, it's essential to note that while they eliminate some environmental impacts, PVC production and disposal can contribute to pollution. Therefore, consumers are encouraged to weigh the pros and cons, considering recycled and recyclable options where possible.

Bonding polypropylene to metal can pose a challenge due to the low surface energy of polypropylene, making it difficult for adhesives to adhere. A successful approach involves surface preparation for both the polypropylene and metal surfaces. Start with cleaning both surfaces to remove any contaminants. For polypropylene, a flame treatment can increase its surface energy, making it more receptive to adhesives. On the metal side, abrasion or chemical etching can create a rougher surface for better mechanical bonding. Epoxy, polyurethane, and cyanoacrylate adhesives are suitable choices due to their strong bonding capabilities and chemical resistance. Apply the adhesive according to the manufacturer's instructions, join the surfaces, and allow adequate time for the adhesive to cure. Test the bond strength after curing to ensure a secure bond. This method balances surface treatment and adhesive selection for effective bonding.