Use the periodic table to answer the question.
An illustration shows the periodic table.
Which element has the same number of valence electrons as bromine (Cl)?
Selenium (Se)
potassium (K)
krypton (Kr)
Fluorine (F)
Fluorine (F)
Why are Chorine (Cl) and Fluorine (F) in the same group on the periodic table?
They have similar atomic weights.
They are both colorless.
They have similar reactivity.
They are both metals
They have similar reactivity.
How do you know if a chemical change has taken place? (1 point)
Responses
A loud noise can be heard.
A loud noise can be heard.
The substance has changed from one phase to another (such as solid to liquid).
The substance has changed from one phase to another (such as solid to liquid).
Chemical changes involve breaking something into smaller peices that have the same properties as the origanal substance.
Chemical changes involve breaking something into smaller peices that have the same properties as the origanal substance.
New substances are formed.
New substances are formed.
Why do we balance chemical equations and how does this relate to the Law conservation of matter? (1 point)
Responses
it shows that all compounds remain bonded after the reaction
it shows that all compounds remain bonded after the reaction
it shows that no atoms have been gained or lost during the reaction
it shows that no atoms have been gained or lost during the reaction
it shows that the properties of the elements stay the same after the reaction
it shows that the properties of the elements stay the same after the reaction
it shows that only physical changes follow the Law of Conservation of Mass
it shows that no atoms have been gained or lost during the reaction
Sodium reacts with chlorine to form the compound sodium chloride, or salt. The chemical formula below shows how the two elements combine into a compound.
2Na + Cl2 → 2NaCl
If the total mass of the reactants is 58.44 amu, what will be the total mass of the products?
(1 point)
Responses
58.44 amu
58.44 amu
29.22 amu
29.22 amu
60 amu
60 amu
116.88 amu
116.88 amu
The total mass of the products would be 58.44 amu.
Which procedure could be used to demonstrate that matter is conserved during a physical change?(1 point)
Responses
Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.
Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.
Find the mass of a piece of paper. Tear the paper into a bunch of peices and find the overall mass of all the pieces.
Find the mass of a piece of paper. Tear the paper into a bunch of peices and find the overall mass of all the pieces.
Use a thermometer to determine if heat is released when vinegar and baking soda are mixed.
Use a thermometer to determine if heat is released when vinegar and baking soda are mixed.
Burn wook in you woodstove and measure the heat that is released.
Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.
One molecule of Oxygen gas (O2) and two molecules of Hydrogen gas (H 2
) combine in a reaction. How many atoms are in the products?(1 point)
Responses
Four
Four
Three
Three
Eight
Eight
Six
Six
Use the unbalanced chemical equation to answer the question.
2NaHCO3 → H2O + CO2
Which of the following can be added to the products to balance the equation?
(1 point)
Responses
O2
O 2
H2O
H 2 O
CH2OH
CH 2 OH
Na2CO3
Na2CO3
The image shows a model of sulfuric acid. In the middle is one yellow ball. Four red balls are attached to the yellow ball with sticks. Two of the red balls have a blue ball attached with sticks. In total, there is 1 yellow, 4 red, and 2 blue balls.
The image is a model of sulfuric acid that has a chemical formula of H2SO4. Why is creating models such as this helpful for us to understand molecules?
(1 point)
Responses
The models show us the size of the molecules.
The models show us the size of the molecules.
The models show us what the substance looks like in nature.
The models show us what the substance looks like in nature.
The models help us to have a better understanding of the shape and structure of the molecule.
The models help us to have a better understanding of the shape and structure of the molecule.
The models show us the color of the atoms.
The models help us to have a better understanding of the shape and structure of the molecule.
Use the chemical equation to complete the activity.
2Cu+S→Cu2S2Cu+S→Cu2S
Copper (Cu) reacts with sulfur (S) to form copper sulfide as shown in the equation. A scientist adds 12.7 grams of Cu to 3.2 grams of S to start the reaction. In this reaction, all of the copper and all of the sulfur react. Before running the experiment, the scientist expected the products of the reaction will be a total of 15.9 grams of copper sulfide (Cu2S). The scientists is correct in his/her thinking.
(1 point)
Responses
True
True
False