2. Structure, Bonding, and Properties of Matter Flashcards
Define compounds and explain how they are formed.
Compounds are substances composed of atoms of two or more elements chemically combined.
Chemical bonding involves either transferring or sharing electrons in the outer shells of atoms to achieve the electron arrangement of a noble gas.
Describe the formation of ions and their relationship to chemical bonding.
When atoms transfer electrons, they form ions. Between a metal and non-metal.
Atoms losing electrons become positively charged ions, while those gaining electrons become negatively charged ions.
Ionic compounds consist of positively and negatively charged ions held together by strong electrostatic forces, known as ionic bonding.
Explain the formation of ionic compounds involving Group 1 elements and halogens.
Group 1 elements (alkali metals) react with non-metals to form ionic compounds, where the metal ions have a single positive charge. Similarly, halogens (Group 7 elements) react with metals to form ionic compounds, with the halide ions carrying a single negative charge.
Describe the structure and bonding in metals.
Metals consist of giant structures with atoms arranged regularly. The electrons in the outer shell of metal atoms are delocalized, forming a “sea” of free electrons that move throughout the structure, held together by strong electrostatic attractions between positive ions and delocalized electrons. So they can conduct electricity.
How are the properties of ionic compounds related to their structure?
Ionic compounds have regular structures (giant ionic lattices) with strong electrostatic forces of attraction between ions in all directions. This results in high melting and boiling points due to the energy required to break the bonds.
Why do substances with simple molecular structures have relatively low melting and boiling points?
Substances with simple molecular structures have weak forces between molecules (intermolecular forces), which are overcome when the substance melts or boils. These forces are weaker compared to covalent bonds within molecules.
Explain why substances with simple molecular structures do not conduct electricity.
Substances with simple molecular structures do not conduct electricity because the molecules do not have an overall electric charge, and thus there are no free ions or delocalized electrons to carry the current.
How do the properties of graphite differ from those of diamond, and why?
Graphite and diamond are both forms of carbon with different structures. Diamond is very hard due to its giant covalent structure, while graphite is soft and slippery because of its layered structure with weak forces between layers.
What are fullerenes, and what are their potential applications?
Fullerenes are carbon molecules with different numbers of carbon atoms, typically forming spherical or tubular structures.
They have potential applications in drug delivery, lubricants, catalysts, nanotubes for reinforcement, and cosmetics, owing to their unique properties and structure.
What is nanoscience?
Nanoscience refers to structures that are 1–100 nm in size, comprising a few hundred atoms.
Define nanoparticles and explain their unique properties.
Nanoparticles are particles with dimensions in the nanometer range (1-100 nm)
They exhibit properties different from bulk materials due to their high surface area to volume ratio.
What are some potential applications of nanoparticles?
Nanoparticles have diverse applications, including the development of new computers, catalysts, coatings, sensors, construction materials, and cosmetics such as suntan creams and deodorants.
How does the size of nanoparticles contribute to their unique properties?
The small size of nanoparticles leads to increased surface area relative to their volume, altering their behavior and allowing for novel applications.
