Chemical Reactions
Which of the following best describes what happens to iron when it reacts with oxygen?
It forms a new substance called iron oxide.
Which choice correctly describes condensation?
a) phase change from gas to liquid, kinetic energy decreases
b) phase change from liquid to gas, kinetic energy increases
c) phase change from liquid to gas, kinetic energy decreases
d) phase change from gas to liquid, kinetic energy increases
a.) phase change from gas to liquid, kinetic energy decreases
Which statement is true about the atomic number and atomic weight of an element?
Atomic number is the number of protons, atomic weight is the number of protons and neutrons.
Atomic number is the number of neutrons, atomic weight is the number of protons and neutrons.
Atomic number is the number of protons and neutrons, atomic weight is the number of protons.
Atomic number is the number of electrons, atomic weight is the number of neutrons.
Atomic number is the number of protons, atomic weight is the number of protons and neutrons.
Which statement is true?
a. Molecules are made of atoms. Atoms are made of elements. b. Atoms make up elements. Elements make up molecules. c. Elements make up atoms. Molecules make up elements. d. Molecules make up elements. Elements make up atoms.
b. Atoms make up elements. Elements make up molecules.
Why do different substances have different properties?
Different substances have different properties:
a. because of the number of atoms it is made of.
b. because of the elements it is made of.
c. because of where it is found on the periodic table.
d. because of the arrangement of the atoms it is made of.
Different substances have different properties:
d. because of the arrangement of the atoms it is made of.
What is the brownish-red substance that forms on iron when it is left outside in a moist environment?
Iron oxide (rust)
Which of the following statements is true?
a) The particles in a solid have greater freedom of movement than liquids.
b) Liquid particles have less kinetic energy than gas particles.
c) Particles in gas have greater freedom of movement but relatively low kinetic energy compared to liquid particles.
d) The particles in a solid are packed tightly together and can move around each other.
b) Liquid particles have less kinetic energy than gas particles.
What does the atomic number of an element tell you?
a) The number of neutrons in the atom
b) The number of protons in the atom
c) The total mass of the atom
d) The number of molecules in the atom
b) The number of protons in the atom
Which remains the same during a chemical reaction?
a. The temperature of the elements
b. The total number of atoms
c. The total number of compounds
d. All of the above
b. The total number of atoms
Which is an example of a different substance being formed?
a. Glass breaking
b. Metal melting
c. Water freezing
d. Wood Burning
d. Wood Burning
Which of the following is TRUE regarding all chemical reactions?
A. All of these answer choices are true.
B. The type of atoms/elements will always remain the same.
C. The mass will always remain the same.
D. The number of atoms will always remain the same.
A. All of these answer choices are true.
Jessi is completing an investigation. She could conclude a chemical change is taking place if which of the following occurs?
a. The size gets smaller.
b. A new substance forms.
c. The state of matter changes.
d. The shape becomes different.
b. A new substance forms.
Elements in the same column (group) of the periodic table usually have:
a) The same number of protons
b) Similar chemical properties
c) The same atomic mass
d) Completely different properties
b) Similar chemical properties
Which of the following is true about atoms?
a) Atoms can be broken down into molecules
b) Atoms are the building blocks of matter
c) Atoms are made of molecules
d) Atoms are always combined into compounds
b) Atoms are the building blocks of matter
A teacher wants to demonstrate a chemical reaction to her students. Which activity would best demonstrate a chemical reaction?
a. Placing a metal in an acid to create a gas.
b. Measuring the densities of liquid water and ice.
c. Melting a solid piece of aluminum.
d. Filling a balloon with helium gas.
a. Placing a metal in an acid to create a gas.
What happens when two different substances are mixed together?
They can form new substances with the same atoms.
What happens to the particles of a substance when it changes from a solid to a liquid?
a) They move slower and stay in place
b) They move faster and slide past each other
c) They move slower and spread far apart
d) They stop moving completely
b) They move faster and slide past each other
The "Periodic Table" we use today has the elements arranged according to their _______
Increasing Atomic Numbers
Water (H₂O) is a molecule because:
a) It contains only one atom
b) It contains atoms of the same element
c) It contains atoms of different elements bonded together
d) It is a pure element
c) It contains atoms of different elements bonded together
Which of the following is a mixture?
a) Salt (NaCl)
b) Water (H₂O)
c) Sand and iron filings combined
d) Carbon dioxide (CO₂)
c) Sand and iron filings combined
How do chemical reactions occur?
a. Atoms rearrange and reform the original substance.
b. Atoms rearrange, form new substances and new atoms.
c. Atoms rearrange and form new substances.
d. Atoms rearrange into repeating groups of the same substance.
c. Atoms rearrange and form new substances.
Which of the following is an example of a gas changing into a liquid?
a) Ice melting
b) Water boiling
c) Steam condensing on a mirror
d) Sugar dissolving in water
c) Steam condensing on a mirror
The periodic table is arranged in order of:
a) Atomic mass
b) Number of neutrons
c) Atomic number
d) Number of molecules
c) Atomic number
What causes a nail to rust over time?
a) The nail melts and changes shape
b) Atoms in the nail are rearranged to form a new substance (iron oxide)
c) The nail becomes colder and shrinks
d) The nail absorbs water but remains the same
b) Atoms in the nail are rearranged to form a new substance (iron oxide)
What is the main difference between a substance and a mixture?
a) A substance contains only one type of matter, while a mixture contains two or more kinds of matter physically combined
b) A mixture has a fixed composition, while a substance does not
c) A substance can be separated physically, while a mixture cannot
d) Substances are always liquids, while mixtures are always solids
a) A substance contains only one type of matter, while a mixture contains two or more kinds of matter physically combined