chemistry science exam

Question 1

What are the three main components of an atom?

Answer 1

Protons (+), neutrons (0), electrons (–)

Question 2

Define atomic number.

Answer 2

Number of protons

Question 3

What is mass number?

Answer 3

Protons + neutrons

Question 4

What is a molecule?

Answer 4

Two or more atoms bonded

Question 5

Define a lattice.

Answer 5

ordered, repeating arrangements of atoms, ions, or molecules within a crystal structure

Question 6

What is a compound?

Answer 6

Two or more elements bonded

Question 7

What is a mixture?

Answer 7

Substances mixed, not bonded

Question 8

Give an example of a common compound.

Answer 8

H₂O (water), NaCl (salt), O₂ (oxygen gas)

Question 9

How do you calculate the mass number?

Answer 9

Mass number = protons + neutrons

Question 10

Describe the electron configuration for the first 20 elements.

Answer 10

Fill shells: 2, 8, 8 electrons

Question 11

What do Lewis dot diagrams represent?

Answer 11

Show valence (outer) electrons

Question 12

Explain the Bohr model.

Answer 12

Electrons orbit nucleus in shells; explains light emission when electrons jump shells

Question 13

What is an isotope?

Answer 13

Same protons, different neutrons

Question 14

Define an ion.

Answer 14

Atom with charge (gained/lost electrons)

Question 15

What are periods in the periodic table?

Answer 15

Rows (same number of shells)

Question 16

What are groups in the periodic table?

Answer 16

Columns (same outer electrons)

Question 17

What are the characteristics of metals?

Answer 17

Left/middle, conduct electricity

Question 18

Describe non-metals.

Answer 18

Right, do not conduct

Question 19

What are metalloids?

Answer 19

Properties of both metals and non-metals

Question 20

Name the major groups in the periodic table.

Answer 20

• Group 1: Alkali metals
• Group 2: Alkaline earth metals
• Group 17: Halogens
• Group 18: Noble gases

Question 21

What trend occurs with atomic radius?

Answer 21

Increases down, decreases across

Question 22

How does reactivity change in Group 1 and Group 17?

Answer 22

Group 1 more reactive down, Group 17 less reactive down

Question 23

What are valence electrons?

Answer 23

Outer shell electrons; determine reactivity and bonding

Question 24

What is ionic bonding?

Answer 24

Metal + non-metal; electrons transferred

Question 25

List properties of ionic compounds.

Answer 25

* Brittle * Conduct electricity when molten * High melting/boiling point

Question 26

What does a Lewis dot diagram for ionic substances show?

Answer 26

Electron transfer (e.g., Na gives electron to Cl)

Question 27

Define covalent bonding.

Answer 27

Non-metal + non-metal; electrons shared

Question 28

List properties of covalent compounds.

Answer 28

* Can be solid, liquid, gas * Low melting/boiling point * Do not conduct electricity

Question 29

What does a Lewis dot diagram for covalent substances show?

Answer 29

Shared electron pairs (e.g., H₂O, O₂)

Question 30

What are polyatomic ions?

Answer 30

Ions with more than one atom (e.g., SO₄²⁻)

Question 31

What is metallic bonding?

Answer 31

Metals only; sea of electrons

Question 32

List properties of metallic bonds.

Answer 32

* Conduct electricity * Malleable * Ductile * High melting/boiling point

Question 33

What do chemical equations represent?

Answer 33

Word and balanced equations show reactants and products

Question 34

What is the conservation of mass?

Answer 34

Mass is conserved in reactions

Question 35

Describe a combination reaction.

Answer 35

A + B → AB

Question 36

Describe a decomposition reaction.

Answer 36

AB → A + B

Question 37

What is the general form of acid reactions?

Answer 37

* Acid + Metal → Salt + H₂ * Acid + Base → Salt + Water * Acid + Carbonate → Salt + Water + CO₂

Question 38

Define solute.

Answer 38

Dissolved substance

Question 39

What is a solvent?

Answer 39

Does the dissolving

Question 40

What does soluble mean?

Answer 40

Can dissolve

Question 41

What does insoluble mean?

Answer 41

Can't dissolve

Question 42

What occurs in precipitation reactions?

Answer 42

Two solutions form an insoluble solid

Question 43

What are net ionic equations?

Answer 43

Only show ions that form the precipitate

Question 44

Define relative atomic mass.

Answer 44

Average mass of atoms (compared to carbon-12)

Question 45

How do you find atomic mass on the periodic table?

Answer 45

Find atomic mass under element symbol

Question 46

How do you calculate masses for molecules/compounds?

Answer 46

Add atomic masses for molecules/compounds

Question 47

What is one mole equivalent to?

Answer 47

6.02 × 10²³ particles (Avogadro’s number)

Question 48

How do you calculate moles?

Answer 48

Moles = mass (g) / molar mass (g/mol)

Question 49

What factors affect reaction rates?

Answer 49

* Temperature * Concentration * Surface area * Catalysts * Agitation * Pressure

Question 50

What does collision theory state?

Answer 50

Particles must collide with enough energy to react

Question 51

What happens to reaction rate with higher temperature?

Answer 51

Higher temperature = more energy = more collisions = faster reaction

Question 52

Fill in the blank: Fast reactions are often characterized by _______.

Answer 52

explosions

Question 53

Fill in the blank: Slow reactions include processes like _______.

Answer 53

rusting