Define Hardness
Measure of resistance that a solid matter shows to kinds of permanent deformation
Define Melting Point
The point of temperature that melts a soild
What are Mechanical characteristics
Stiffness, Strength, and toughness
Define Conductivity
Measure of a solid’s ability to conduct electricity
Define Facture
The way a solid breaks
What are the four classes of solids
- Ionic (metal+nonmetal)
- Metallic (metals)
- Molecular (non-metals)
- Covalent network (semi-metal/non-metals)
Ionic Crystals
- Metal + non metal
- Usually solid
- Ionic compounds are not very reactive and have filled energy lvls
- Transfer in electrons bcs of DEN
- Create strongest bond bcs neg and pos charges approach as close as possible
- High BP
Crystal lattice
Crystalline repeating pattern of atoms making solid structure
- Crystal lattice ions cannot be rearranged w/o breaking
Metallic Crystals
- Shiny, silvery, flexible, solid, good conductors
- Valence electrons become mobile bcs they are not held tightly, making them good conductors
- Flexible bcs non-directional bonds allow planes f ions to slide over each other easily while remaining bonded.
Molecular Crystals
- Low melting point, not hard, non conductors
- Molecules stacked as close as possible
- Intermolecular bonds are not strong = low melting points
Covalent network
- Hard, brittle, high BP, insoluble, non conductors
- 3-D arrangement of atoms continuously linked throughout the crystal by covalent bonds
- Covalent bonds are stacked = high melting point
- Electrons cannot move easily = cannot conduct electricity.
Group 1 (PT)
- Alkali Metals
- React w/ water to form alkaline (basic) solutions
- Most reactive
Group 2 (PT)
- Alkaline Earth Metals
- React w/ oxygen to form compounds called xides which reaction with water to form alkaline (base) solutions
Group 17 (PT)
- Halogens
- React w/ other elements to form compounds known as salts
Group 18 (PT)
- Noble Gases
- Do not combine naturally w/ any other elements
- Least reactive
Qualitative Properties
- Properties that are observed (not really measured)
Ex. Conductivity, malleability, color, odor, size, texture,
Quantitative Properties
- Properties that are measured
Ex. Density, volume, mass, BP
Define and name the Molecular Elements
Molecules containing two or more of element
I2, Br2, Cl2, F2, O2, N2, H2, P4, S8
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