Chemistry Midterm 23-24

All of the following are physical properties of silicon except--

• Silicon has a blue-gray color.

• Silicon is a brittle solid at 20 degrees Celsius.

• Silicon melts at 1414 degrees Celsius.

• Silicon reacts with fluorine.

Which Process results in a chemical change? (4a)

• Tearing aluminum foil

• Melting an iron bar

• Burning magnesium ribbon

• Crushing a steel can

A chemistry student's investigation is described above.  The student determines that the substance is sodium chloride.  Which of the following is an extensive property of sodium chloride?         (4B)

• Mass is 15 grams.

• Color is white.

• Density is 2.17 cm³

• Substance is soluble in water.

Which of these statements correctly describes how solids, liquids, and gases are different?   (4C)

• Liquids and solids have a shape of their own; only gases have no definite shape.

• Only gases can be compressed; solids and liquids cannot be compressed.

• Only solids have a definite volume; liquids and gases have no definite volume.

• The particles in solids and liquids are locked in place; particles are free to move around each other in gases.

Which type of matter has two or more elements that are chemically combined?

• elements

• solutions

• mixtures

• compounds

Which two physical properties allow a mixture to be separated by filtration?

• Solubility and particle size

• Density and specific heat

• Hardness and boiling point

• Electrical and thermal conductivity

Use the key above to determine which diagram represents a mixture of two different forms of the same element.   (4D)

• 
• 
• 
• 

How did Mendeleev organize his periodic table?

• Elements were placed in order of their discovery.

• The names of the elements were in alphabetical order.

• Elements were arranged by their atomic mass.

• Elements were arranged by their atomic number.

Why are the noble gases (group 18) the most unreactive elements?

• The noble gas elements have large atoms.

• The noble gases have an equal number of protons and electrons in their
  atoms.

• The noble gas atoms have a total of 8 valence electrons or a full valence shell.

• The noble gases have very low boiling and freezing points.

Refer to the periodic table. In which list are the elements in order from smallest to largest atomic radius? (5C)

• K, Na, Li

• F, O, N

• B, C, N

• S, F, He