What are valence electrons?

Electrons on the outermost shell.

A substance that dissolves another substance.

If an atom loses an electron during a chemical reaction, is the atom positive or negative? Why?

Postive, the atom now has more protons than electrons.

What elements WILL bond with other elements?

Elements that don't have full valence electron, Group 1 -17.

What is specific heat?

The amount of heat needed to raise the temp 1 degree C

In our lab, Acetone and Styrofoam, did we create a heterogeneous or homogenous solution? Why?

We created a heterogeneous solution- not evenly mixed.

What is the Law of Conservation of Matter? Pick 2:)

Total mass of reactants equals the total mass of products., Matter cannot be destroyed or created in chemical reactions.

Which is NOT a main idea about chemical reactions?

Chemical reactions create phase changes only.

What are the 3 subatomic parts of an atom? Charges too, please!

Protons (+), Neutrons (nc), Electrons (-)

Phase change, solid to a gas w/o an intervening liquid stage

Is the Diet Coke and Mentos a physical or chemical? Explain.

Physical- No "new" molecules created, just released the CO2.

What is a chemical reaction?

Change of a sub. into a "new" that has a diff. chemical id.

For the lab Ghost Gas, the reactants would be 20 grams, the products would be 18 grams. Why?

The 2 grams were carbon dioxide compounds, released as gas.

The substance that is dissolved into another substance.

Most basic part of matter, made of 1 or more identical atoms

What is a period of the periodic table? Location and meaning?

Rows, left to right. Shows how many shells elements have.

Anything that has mass and volume

What is malleability?

Ability to be hammered or shaped into thin sheets.

What are precipitates?

Solid that forms from 2 liquids during a chemical reaction.

What is a group of the periodic table?

Column, shows how many valence electrons elements have.

Force of attraction or repulsion between poles.

What are nucleation sites?

Tiny pits on mentos that collect CO2

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Chemistry Quiz! 2025

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Chemistry Unit Review- Grade 8

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Questions 38

Answers

1
What is a catalyst?
A substance that inhibits a chemical reaction.
Yeast
Hydrogen Peroxide
A substance that causes or accelerates a chemical reaction.
2
What is Density?
The ratio of mass to volume (G/cm3 or g/ml)
The ratio of protons to neutrons (+/n)
The ratio of height to weight (meters/grams)
The ratio of hard work to success (w/s)
3
What are valence electrons?
All protons plotted on shells.
Protons on the outermost shell.
Electrons on the outermost shell.
All electrons plotted on shells.
4
What is a solvent?
A substance that dissolves another substance.
A mixture of 2 or more substances.
A substance that is dissolved.
A chemical product.
5
If an atom loses an electron during a chemical reaction, is the atom positive or negative? Why?
Postive, the atom now has more electrons than protons.
Negative, it's an angry element.
Postive, the atom now has more protons than electrons.
Negative, the atom now has more electrons than protons.
6
Which is NOT one of the 5 clues you had a chemical reaction?
Phase Change
Change in color
Release of energy
Formation of a gas
7
What elements WILL bond with other elements?
Elements that DO have full valence electrons- Group 18.
Elements with a capital letter.
Elements that don't have full valence electron, Group 1 -17.
Noble gases
8
Materials that can be stretched into wires without breaking are called
Conductor
Insulator
Malleable
Ductile
9
What is specific heat?
Amount of heat needed to create a solar flare
The specific amount of heat needed for cellular respiration.
The amount of heat needed to reduce the temp 1 degree C
The amount of heat needed to raise the temp 1 degree C
10
What elements (1-20) have complete outer shells? What do we call these?
Be, Mg, Ca- Alkaline Earth metals.
He, Ne, Ar- Noble gases
H, li, Na, K- Alkali
F, Cl, Br- Halogens
11
In our lab, Acetone and Styrofoam, did we create a heterogeneous or homogenous solution? Why?
We created a homogenous solution- not evenly mixed.
We created a heterogeneous solution- not evenly mixed.
We created a homogenous solution- evenly mixed.
We created a heterogeneous solution- evenly mixed.
12
What is the Law of Conservation of Matter? Pick 2:)
Total mass reactants don't equal the total mass of products.
Matter can be created or destroyed by physical reactions.
Total mass of reactants equals the total mass of products.
Matter cannot be destroyed or created in chemical reactions.
13
Which is NOT a main idea about chemical reactions?
Balanced equations have same elements and number of atoms.
Chemical reactions create phase changes only.
Atoms are arranged to form "new" substances.
Matter can't be created or destroyed, mass stays the same.
14
What are the 3 subatomic parts of an atom? Charges too, please!
Protons (+), Neutrons (-), Electrons (nc)
Protons (-), Neutrons (nc), Electrons (+)
Protons (nc), Neutrons (+), Electrons (-)
Protons (+), Neutrons (nc), Electrons (-)
15
Beaker Ball Lab, you throw 15 skittles into the beaker, what element is that?
Phosphorus
Sodium
Sulfer
Boron
16
What is sublimation?
Phase change, solid to liquid
Phase change, liquid to a solid
Phase change, gas to a solid w/o an intervening liquid stage
Phase change, solid to a gas w/o an intervening liquid stage
17
The Lewis Dot Diagram for He is ....
He⋅
He:
He∴
HeẊ
18
Is the Diet Coke and Mentos a physical or chemical? Explain.
Physical- Solid CO2 changed into a gas.
Chemical- It was chemistry at first sight!
Physical- No "new" molecules created, just released the CO2.
Chemical- We did create "New" molecules
19
Are melting point and freezing point the same temperature?
Elements don't have phase changes.
Depends on the element.
No!
Yes!
20
What is a chemical reaction?
A mixture of two substances.
Atoms stay the same but have a different state of matter.
Change of a sub. into a "new" that has a diff. chemical id.
Make bubbles, odor, precipitate, energy, or color change.
21
For the lab Ghost Gas, the reactants would be 20 grams, the products would be 18 grams. Why?
The 2 grams were carbon dioxide compounds, released as gas.
This is a haunting.
The Law of Conservation doesn't apply to mass.
The ghost took the 2 grams away
22
What is a solute?
The substance that is dissolved into another substance.
The substance that is dissolving another substance.
The product of a chemical reaction.
A mixture of 2 or more substances.
23
What is an element?
Most basic part of matter, made of 1 or more identical atoms
Type of a rock
Made of 1 or more different types of atoms.
Has protons, neutrons, and electricity
24
If you have 15 as the Atomic Number, this means you have ________?
15 protons or 15 electrons
15 neutrons and 15 electrons
15 protons and 15 neutrons
You have a noble gas.
25
What is a period of the periodic table? Location and meaning?
Rows, left to right. Shows how many valence electrons.
Columns, up and down. Shows how many valence electrons.
Columns, up and down. Shows how many shells elements have.
Rows, left to right. Shows how many shells elements have.
26
Where are metalloids located on the periodic table?
in the far left column
in the top row
in the far right column
along a step-like line
27
What is an endothermic reaction?
A reaction that occurs inside the baggie.
Releases energy, feels hot
Absorbs energy, feels cold.
An explosion
28
What is matter?
The small part of element that has all the same properties.
Anything that has mass
Anything that has volume
Anything that has mass and volume
29
What is malleability?
Allows electrons to flow through easily.
Ability to carry a current.
Ability to be flexible.
Ability to be hammered or shaped into thin sheets.
30
What are precipitates?
Rain, snow or ice.
Bubbles, color change, odor, or temperature change
Solid that forms from 2 liquids during a chemical reaction.
Solid that forms from 2 liquids during a physical reaction.
31
In Ghost Gas, HC₂H₃O₂+ NaHCO₃→NaC₂H₃O₂+CO₂+H₂O. What are the reactants?
NaC2H3O2+CO2+H2O
Sodium Acetate+Carbon Dioxide+Water
Water
HC2H3O2 + NaHCO3
32
A type of matter forms when two or more elements combine chemically.
Compound
Element
Mixture
Pure substance
33
How many groups are there?
12
18
8
24
34
What is a group of the periodic table?
Column, shows how many valence electrons elements have.
Row, shows how many shells an element has.
Row, shows how many valence electrons elements have.
Column, shows how many shells elements have.
35
What is magnetism?
Force of atoms colliding with other atoms.
Force of attraction or repulsion between poles.
Force to sticking together, cohesion.
Force of sticking to other substances, adhesion.
36
Mg + O₂→ MgO. Is this balanced?
No! Mg + 2O2 →4MgO
Yes!
Yes! Same number of atoms on both reactant and product.
No! 2Mg + O2 →2MgO
37
The electrons discussed in class have 3 or fewer shells. How many electrons fit each shell?
18, 8, 2
2, 10, 16
2, 8, 18
2, 8, 16
38
What are nucleation sites?
Sites that allow for chemical reactions to occur.
Places that break the surface tension of diet coke.
Tiny pits on mentos that collect CO2
Place where nuclear reaction occurs.

Chemistry Quiz! 2025 Flashcards | StudBud