CHECK MY ANSWERS!!!!!!!
1) Cobalt has a mass number of 59 and an atomic number of 27. A student wants to create a model of a cobalt atom. Which statement about the model is correct?(1 point)
A. The model should show 27 protons and 32 neutrons.******
B. The model should show 59 protons and 27 neutrons.
C. The model should show 27 protons and 27 neutrons.
D. The model should show 32 protons and 59 neutrons.
2) In a molecule of lithium sulfide, there are two atoms of lithium and one atom of sulfur. Which statement about lithium sulfide is correct?(1 point)
A) The chemical formula for lithium sulfide is LiS2.
B) The atoms in lithium sulfide are held together by bonds.*****
C) Both lithium and sulfur form positive ions.
D) A molecular model of lithium sulfide would have two spheres.
3)Which element has the same number of valence electrons as bromine (Br)? (1 point)
A) ytterbium (Yb)
B) selenium (Se)
C) krypton (Kr)******
D) astatine (At)
4) Why are sodium (Na) and potassium (K) in the same group on the periodic table?(1 point)
A) They have similar reactivity.*******
B) They are both hard and brittle.
C) They have similar atomic weights.
D) They are both colorless.
5) A student cuts some fabric into two pieces. Is this change physical or chemical?(1 point)
A) It is a chemical change because there is no phase change.
B) It is a chemical change because the size changes.
C) It is a physical change because the process is reversible.
D) It is a physical change because there is no reaction.******
6) How are chemical changes different from physical changes?(1 point)
A) They form new substances.********
B) They are reversible.
C) They involve heat.
D) They include shifts in the phase of matter.
7)A scientist makes several observations about a chemical reaction and records them in the table shown. Which observation contains an error? (1 point) picture added!
A) 1
B) 3
C) 2******
D) 4
8) In a chemical reaction, hydrofluoric acid (HF) and sodium hydroxide (NaOH) combine to form sodium fluoride (NaF) and water (H2O). The reaction uses 20 grams of hydrofluoric acid and 40 grams of sodium hydroxide, and it produces 18 grams of water. How much sodium fluoride does the reaction produce?(1 point)
A) 60 grams
B) 42 grams
C) 18 grams******
D) 78 grams
9)Which procedure could be used to demonstrate that matter is conserved during a physical change?(1 point)
A) Find the mass of an apple. Cut the apple and remove the core. Find the mass of the remaining apple.
B) Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.********
C) Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.
D) Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
10) One molecule of bromine (Br2) and two molecules of potassium chloride (KCl) combine in a reaction. How many atoms are in the products?(1 point)
A) two******
B) four
C) three
D) six
11) Use the unbalanced chemical equation to answer the question.
2NaHCO3 → Na2CO3 + CO2
What can be added to the products to balance the equation? (1 point)
A) CH2OH****
B) H2O
C) H2
D) O2
12) The chemical formula for phosphorus trichloride is PCl3. In one to two sentences, explain how you would build a ball-and-stick model of phosphorus trichloride. Include a description of the parts of the model.(2 points)
13) Copper (Cu) reacts with sulfur (S) to form copper sulfide as shown in the chemical equation. A scientist adds 4 grams of Cu to 2 grams of S to start the reaction. At the end of the experiment, she has 6 grams of product. In one to two sentences, explain what would happen if the scientist increased the amount of copper to 6 grams, and why. (1 point)
99 answers
1. b
2. b
3. b
4. c
5. c
6. a
7. b
8. b
9. c
10. c
11. d
12 and 13 you answer on yr own < 33
Correct answers are
1.c
2.c
3.a
4.b
5.a
6.c
7.b
8.b
9.b
10.d
11.c
and then the last two are on your own. Yw btw
2. The atoms in lithium sulfide are held together by bonds.
3. astatine (At)
4. They have similar reactivity
5. It is a physical change because there is no reaction.
6. They form new substances
7. 1
8. 42 grams
9. Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
10.six
11. H20
12 and 13 on your own:)
1. The neutron has a negative charge and is found in the nucleus.
2. The model should show 27 protons and 32 neutrons
3. because only two electrons can fit in the first orbit around the nucleus, and each period on the table is organized by number of orbits
4. The atoms in lithium sulfide are held together by bonds.
5. Astatine (At)
6. atomic number
5. low-energy alpha particles passing through a field of high mass-number-particles
7. Metals can be hammered into thin sheets, and nonmetals are brittle.
8. polonium (Po)
9. silicon (Si)
10. Hydrogen has one electron and one proton.
11.Barium has fewer valence electrons, but they are in a higher energy level.
12. Barium has more valence electrons, and they are in a higher energy level. (Maybe?)
13. An ionic bond is likely because they will want to give away two valence electrons in order to become stable.
14. 2-
15. four
16. OH
17. methyl
18. You could use a red ball for P and 3 yellow for CI. (Change The Colors, wink wink.)
19. For Instance, Neon (Ne) has an atomic number of 11. It has a completely full Shell of electrons. But Sodium has 1 more proton, AND one more electron. That extra electron is in the outside shell, making a VALENCE electron. (ParaphraseortheywillfindoutandthenyouwillbeDED.)
20. On the table metals, (which you can find on the left side) the metals will be positive. On the right side, the NON-metals will be negative. (againyoubetterparaphraseyoulittlesonsof)
Well, that's all, I'm of to mess with jack. (I swear, if he buys one more tub of antiseptic cream for Christmas for me, i'ma SNAP.)
1. the neutron has a negative charge and is found in the nucleus
9. vanadium(v)
11. hydrogen doesnt have any neutrons
12. francium has fewer valence electrons, but they are in a higher energy level
everything else is good! ty anti, have fun messing w jack<3
If you have red balls for phosphorus, the sticks for bonds, and white balls for trichloride, then you would need 1 red ball, 3 sticks, and 3 white balls. the sticks will connect all of the molecules together, with the red ball as the base and then a white ball sticking out of 3 different spots.
You can weigh the reactants. The mass and products will be the same.
AGAIN DON'T USE MY ANSWERS WORD FOR WORD!!!!!!!!!!!
1. The model should show 27 protons and 32 neutrons.
2. The atoms in lithium sulfide are held together by bonds.
3. chlorine (Cl)
4. They have similar reactivity.
5. It is a physical change because there is no reaction.
6. They form new substances.
7. 1
8. 42 grams
9. Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
10. six
11.H2O
this for ppl who use Conexxus i flunked the test so im just gunna grab awnsers from the awnser key at the end :>
1.The model should show 27 protons and 32 neutrons.
2.The atoms in lithium sulfide are held together by bonds
3.chlorine (Cl)
4.They have similar reactivity.
5.Vinegar
6. 1
7. It is a physical change because there is no reaction.
8.They form new substances
9. 1
10. 42 grams
11. Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
12. six
13. H2O
14 - 15 are writing questions good luck on those endings :> sry if you got these wrong bc they changed the awnsers
The same ones everyone else said but 8 is 58.44 and 9 is find the mass of a peice of ice let the ice melt find the madd of the luquid water
And good day!
2. The atoms in lithium sulfide are held together by bonds.
3. Chlorine
4. They have similar reactivity
5. It is physical change because there is no reaction
6. They form new substances
7. It shows that no atoms have been gained or lost during the reaction
8. 58.44 amu
9: find the mass of a pride of ice. Key the ice melt. Find the mass of the liquid water.
10. Six
11. H2O
12 and 13. Do it yourself.
A model aids in visualizing a molecule and understanding its properties.
In chemistry, models of molecules give us an idea about the arrangement of atoms in the molecules. Usually, the arrangement of atoms in a molecules determines the kind of reactions that the molecule can undergo.
Models are three dimensional representations of what molecules look like. They help us to conceptualize the possible orientation of atoms and groups in the molecule.
Which element has the same number of valence electrons as bromine(Br)?
selenium (Se)
krypton (Kr)
potassium (K)
chlorine (Cl)****
2.B
3.D
4.D
5.C
6.A
7.D
8.C
9.D
10.D
11.C
12.If you have red balls for phosphorus, the sticks for bonds, and white balls for trichloride, then you would need 1 red ball, 3 sticks, and 3 white balls. the sticks will connect all of the molecules together, with the red ball as the base and then a white ball sticking out of 3 different spots.
13.You can weigh the reactants. The mass and products will be the same.
AGAIN DON'T USE MY ANSWERS WORD FOR WORD!!!!!!!!!!! :)
An illustration shows the periodic table.
Which element has the same number of valence electrons as bromine (Br)?
(1 point)
Responses
chlorine (Cl)
chlorine (Cl)
potassium (K)
potassium (K)
krypton (Kr)
krypton (Kr)
selenium (Se)
13: Because he added the reactants' mass together, and the Law of Conservation of Mass states that no atoms may be created or destroyed, only change.
PARAPHRASE! DO NOT USE WORD FOR WORD!
Also, to the no cheating people, kinda hard when you're lucky when the teacher teaches relevant information, plus you gotta admit cheating's the reason why you're here, hypocrites.
30 answers