CHEM|1st summative

Question 1

are arranged in fixed geometric patterns or lattices.
Examples are ice and sodium chloride (NaCl), copper sulfate (CuSO4), diamond, graphite, and sugar (C12H22O11). The ordered arrangement of their units maximizes the space they occupy and are essentially incompressible

Answer 1

Crystalline solids

Question 2

have a random orientation of particles. Examples are glass, plastic, coal, and rubber. They are considered super-cooled liquids where molecules are arranged in a random manner
similar to the liquid state

Answer 2

Amorphous solids

Question 3

More than 90% of naturally occurring and artificially prepared solids are ___________. . Minerals, sand, clay, limestone, metals, alloys, carbon (diamond and graphite), salts (e.g. NaCl and MgSO4), all have_______________________. They have structures formed by repeating three dimensional patterns of atoms, ions, or molecules.

Answer 3

crystalline structures

Question 4

Four Types of Crystals

Answer 4

1. METALLIC CRYSTALS
2. IONIC CRYSTALS
3. MOLECULAR CRYSTALS
4. COVALENT NETWORK CRYSTALS

Question 5

are made of atoms that readily lose electrons to
form positive ions (cations), but no atoms in the crystal would readily gain electrons. The metal atoms give up their electrons to the whole crystal, creating a structure made up of an orderly arrangement of cations surrounded
by delocalized electrons that move around the crystal. The crystal is held together by electrostatic interactions between the cations and delocalized electron. These interactions are called metallic bonds. This model of metallic bonding is called the “sea of electrons” model.

Answer 5

Metallic crystals

Question 6

Dense, High Melting Point, Good electrical conductor, good heat conductor, malleable and ductile, lustrous

Answer 6

Metallic Crystals

Question 7

are made of ions (cations and anions). These ions form strong electrostatic interactions that hold the crystal lattice together. The electrostatic attractions are numerous and extend throughout the crystal since each ion is surrounded by several ions of opposite charge, making ionic crystals hard and of high melting points.

Answer 7

Ionic crystals

Question 8

Hard, High Melting Point, Poor electrical conductor in the solid state, good electeical conductor in the molten state, brittle

Answer 8

Ionic crystals

Question 9

are made of atoms, such as in noble gases, or molecules, such as in sugar, C12H22O11,iodine, I2, and naphthalene, C10H8. The atoms or molecules are held together by a mix of hydrogen bonding/dipoledipole and dispersion forces, and these are the attractive forces that are broken when the crystal melts. Hence, most molecular crystals have relatively low melting points.

Answer 9

Molecular crystals

Question 10

Soft, Low Melting Point, Poor Electrical conductor in the solid and molten states, poor heat conductors, brittle

Answer 10

Molecular crystals

Question 11

are made of atoms in which each atom is covalently bonded to its nearest neighbors. The atoms can be made of one type of atom (e.g. Cdiamond and Cgraphite) or can be made of different atoms (e.g. SiO2 and BN). In a network solid, there are no individual molecules and the
entire crystal may be considered one very large molecule. Formulas for network solids, like those for ionic compounds, are simple ratios of the component atoms represented by a formula unit.

Answer 11

Covalent network crystals

Question 12

Hard, Very High Melting Point, Poor electrical conductor in the solid and molten states, poor heat conductor, brittle

Answer 12

Covalent network crystals