1. STANDARD 3a
Students know the structure of the atom and know it is composed of protons, neutrons, and electrons

2. Structure of Matter
All matter is made up of small particles called atoms
An atom is the smallest unit of an element
Composed of three particles
Protons – positively charged particles in the nucleus (center)
Neutrons – particles with no charge located in the nucleus
Electrons – negatively charged particles surrounding the nucleus in shells also known as energy levels
Most of the atom’s mass is located in the nucleus

3. Structure of Matter 18. Which of the following best describes an atom?
A Protons and electrons grouped together in a random pattern
B Protons and electrons grouped together in an alternating pattern
C A core of protons and neutrons surrounded by electrons
D A core of electrons and neutrons surrounded by protons
ANSWER: C

4. Structure of Matter ANSWER: C
20. The diagram above shows models of two different atoms. Which subatomic particles are represented by the black dots?
A protons
B neutrons
C electrons
D nuclei
ANSWER: C

5. Structure of Matter A electrons only B protons only C neutrons only
22. Which particles in an atom account for nearly all the atom’s mass
A electrons only
B protons only
C neutrons only
D protons and neutrons
ANSWER: D

6. STANDARD 3b
Students know that compounds are formed by combining two or more different elements and that compounds have properties that are different from their constituent elements

7. COMPOUNDS All matter is made of elements
In nature, most elements are found combined with other elements because most atoms are unstable
When atoms combine, they form a chemical bond, which is a force of attraction between two atoms
A compound is a substance made of two or more elements chemically combined in a set ratio. Water molecule is always made up of two hydrogen atoms to one oxygen atom.

8. COMPOUNDS
Valence electrons are the electrons that have the highest energy level and are held most loosely because they are farthest away from the nucleus
Atoms become stable (or happy) when they have a total of 8 valence electrons. All atoms except the noble gas atoms have fewer than 8 valence electrons
Atoms achieve 8 valence electrons by bonding with other atoms
Two main types of chemical bonds: ionic bonds and covalent bonds
An ion is an atom or group of atoms that has an electric charge: positive or negative

9. COMPOUNDS
Ionic Bond: a chemical bond that forms as a result of the attraction between positive and negative ions
Covalent Bond: a chemical bond that forms when two atoms share valence electrons
A molecule is a neutral group of two or more atoms joined by covalent bonds
Water is a molecular compound with a chemical formula of H2O

10. COMPOUNDS
24. Which of the following chemical formulas represents a compound?
A He
B O2
C HCl
D Sn
ANSWER: C

11. COMPOUNDS 26. The atoms in a molecule of water are joined by
A ionic bonds
B covalent bonds
C unshared electrons
D shared protons
ANSWER: B

12. COMPOUNDS
27. Magnesium reacts with oxygen to form MgO. Properties of MgO are most likely
A similar to magnesium
B similar to oxygen
C different from magnesium or oxygen
D similar to both magnesium and oxygen
ANSWER: C

13. STANDARD 3c
Students know atoms and molecules form solids by building up repeating patterns, such as the crystal structure of NaCl or long-chain polymers

14. STRUCTURE OF COMPOUNDS
Ionic compounds form solids by building up repeating patterns of ions.
The result is a solid with an orderly, three dimensional arrangement called a crystal
Solid ionic compounds are hard and brittle, have high melting points and when melted or dissolved conduct electricity

15. STRUCTURE OF COMPOUNDS
Molecular compounds contain atoms that are covalently bonded, forming molecules
Molecular compounds have low melting and boiling points and do not conduct electricity

16. STRUCTURE OF COMPOUNDS
Some molecular compounds are composed of polymers
A polymer is a very large molecule made of a chain of many repeating, smaller molecules bonded together
Many of the molecules that make up living things are polymers: proteins, DNA, carbohydrates
Glucose
Amino acid
Nucleotide

17. STRUCTURE OF COMPOUNDS
28. Which is not a characteristic of a molecular compound?
A low melting point
B does not conduct electric current
C low boiling point
D hard, brittle solids at room temperature
ANSWER: D

18. STRUCTURE OF COMPOUNDS
29. What type of structure is shown in the diagram?
A atom
B crystal
C molecule
D polymer
ANSWER: B

19. STRUCTURE OF COMPOUNDS
30. Which of the following kinds of force helps hold the particles together?
A electrical attraction
B magnetic attraction
C gravitational attraction
D thermonuclear attraction
ANSWER: A

20. STRUCTURE OF COMPOUNDS
31. Some compounds found in the human body are long chains of smaller molecules. These chains are called
A carbon molecules
B covalent bonds
C polymers
D crystals

21. STANDARD 3d
Students know the states of matter (solid, liquid, gas) depend on molecular motion

22. Molecular Motion
32. Which type of motion best represents the movement of gas particles?
A Motion 1
B Motion 2
C Motion 3
D Motion 4
ANSWER: A

23. STANDARD 3e
Students know that in solids the atoms are closely locked in position and can only vibrate; in liquids the atoms and molecules are more loosely connected and can collide with and move past one another; and in gases the atoms and molecules are free to move independently, colliding frequently

24. Molecular Motion
Solid
Liquid
Gas

25. Molecular Motion Definite shape and volume Lowest energy
Tightly packed together
Does not take the shape of its container
SOLID
Definite volume but no definite shape
Slightly higher energy than solids
Molecules slide past one another
Takes the shape of its container
LIQUID
No definite shape or volume
Highest energy
Molecules move throughout the container
Takes shape of container
GAS

26. CHANGES OF STATE
A change of state is the conversion of a substance from one physical form to another.
All changes of state are physical changes.
During a change of state, energy of a substance changes. Energy is either released or absorbed

27. CHANGES OF STATE Melting – from a solid to a liquid
Freezing – from a liquid to a solid
Vaporization – from a liquid to a gas
Boiling – takes place throughout the liquid
Evaporation – takes place only on the surface
Condensation – from a gas to a liquid
Sublimation – from a solid to a gas

28. CHANGES OF STATE

29. CHANGES OF STATE 33. What occurs when liquid water becomes ice?
A Energy is added to the water, so its molecules move more slowly
B Energy is added to the water, so its molecules move more quickly
C Energy is removed from the water, so its molecules lock into place
D Energy is removed from the water, so its molecules move apart
ANSWER: C

30. Changes of State
34. The graph shows the effect of adding energy to water at sea level. When the temperature reaches 100 degrees Celsius, what happens to the water molecules as energy continues to be added?
A. The water molecules gain energy as the temperature continues to rise
B The water molecules gain no energy and the temperature stays the same
C The water molecules become more ordered as the state changes to a gas
D The water molecules move farther apart as the state changes to a gas
ANSWER: D

31. CHANGES OF STATE
35. The diagram illustrates the particles of a solid substance held in a container. What would happen if the substance gained enough energy so that it melted completely?
A The particles would remain locked together in the same shape
B The particles would spread out into a layer that fills the bottom part of the container
C The particles would spread apart widely and fill the entire container
D The particles would chemically change into new substances
ANSWER: B