chem Flashcards
(39 cards)
What is a limiting reactant?
The limiting reactant is the reactant that produces the smaller mass after stoichiometry.
What are the limitations of the ball and stick model?
It shows where bonds are but does not represent bonds as physical entities.
What does a displayed formula show?
It shows all bonds clearly but lacks a 3D structure.
What does the particle model illustrate?
It shows the forces between particles, their sizes, and the space between them.
What is the empirical formula useful for?
It is good for larger molecules but lacks structural knowledge.
What does a molecular formula provide?
It shows the exact number of atoms but no structural information.
What are typical atomic radii and bond lengths?
They are typically 10^-10 m; bond length is the distance between the centers of two joined atoms.
What is the mass of an electron?
Electrons have a mass of 0.0005.
What is chromatography?
Chromatography is a technique involving a stationary phase and a mobile phase for separating components.
What is the Rf value in chromatography?
Rf = distance travelled by substance / distance travelled by solvent.
What are the stages of gas chromatography?
- Turned into gas 2. Injected into column 3. Carrier gas pushes it through column 4. Detector records when components leave.
What is the process of crystallization/distillation?
A solution is heated gently until saturation, crystals form, and as it cools, more crystals form.
What did Mendeleev consider when arranging the periodic table?
He considered atomic weight, chemical reactions, and physical properties.
How did Mendeleev arrange elements?
He arranged them by atomic weight and grouped those with similar chemical properties.
What did Ramsay discover in 1894?
Ramsay discovered argon.
What are the properties of metals?
Metals are conductors, malleable, have high boiling points, are shiny, dense, and form alkali oxides.
What are the properties of non-metals?
Non-metals are insulators, brittle, have low boiling points, are dull, light, and form acidic oxides.
What is diamond’s structure and properties?
Diamond has a giant covalent structure, high melting point, is hard, and cannot conduct electricity.
What is graphite’s structure and properties?
Graphite has a layered structure, conducts electricity, and is slippery due to weak intermolecular forces.
What is graphene?
Graphene is a single layer of carbon atoms, transparent, strong, and conducts electricity.
What is a nanotube?
A nanotube is a sheet of graphene rolled into a tube, used to reinforce sports equipment.
What is buckminsterfullerene?
Buckminsterfullerene is a hollow ball made from a sheet of graphene, can have pentagons and hexagons.
What is the difference between thermosoftening and thermosetting polymers?
Thermosoftening polymers are tangled and easy to separate, while thermosetting polymers have strong covalent bonds.
What characterizes metallic bonds?
Metallic bonds consist of a sea of delocalised electrons surrounding positive metal ions.
