CHEMISTRY MIDDLE SCHOOL

Why are the masses of some elements listed as whole numbers in parentheses?

Answers

Answer 1
Answer:

Answer:

Explanation: Both Protons and The Neutrons in an atom have a relatively equal mass.


Related Questions

HIGH SCHOOL

Is a building part of the society or part of the environment? (If buildings are being broken down, is it an environmental or social impact?)

Answers

This question is very vague but I see that you posted it in Chemistry.

We can then assume that a chemical reaction is occurring that most be breaking down the building, an example being rust or corrosion.  This would be environmental damage.

However, a building can be considered both a part of society and the environment depending on how you look at it.  Also, it can both have environmental and social impact if its being broken down.
It depends on the buildings material. if it has asbestos or SBS or mold of some type, it would both social, and environmental. if the building is a modern structure with no complications, then it is just social.
HIGH SCHOOL

What formula is MaVa=MbVb?

Answers

I don't know if this helps...but it is a titration formula.
HIGH SCHOOL

2 O2 + CH4 CO2 + 2 H2O What mass of oxygen is required to completely react with 2 moles of CH4? 6 C 12.01 Carbon 1 H 1.01 Hydrogen 8 O 16.00 Oxygen

Answers

3rd one is the correct answer!
HIGH SCHOOL

At 900 °C titanium tetrachloride vapor reacts with molten magnesium metal to form solid titanium metal and molten magnesium chloride.Which substance is the reductant, and which is the oxidant?

Answers

Part A.

Let the oxidation number of Ti in titanium tetrachloride be 'x'. The oxidation number of the chlorine atom is -1.

Thus,

x + 4(-1) = 0

or x = +4

In the products, Ti is present in the elemental state and thus its oxidation number is zero. Thus, the oxidation number is reduced.

Magnesium is in the elemental state in the reactant with oxidation number zero and in the products, it is present as magnesium chloride. Let the oxidation no. of Mg in magnesium chloride be 'y'.

Thus,

y + 2(-1) = 0

or, y = +2

Thus, the oxidation state of Mg is increased.

Thus,

Mg is oxidized

T
i
C
l
4
is reduced.

_____

Part C:

The reductant (or reducing agent) is a species that itself gets oxidized and reduces other species. Oxidant (or oxidizing agent) is a species that itself gets reduced and oxidizes the other species.

Thus, the reductant is Mg and oxidant is
T
i
C
l
4

COLLEGE

The goose has a mass of 22.6 lb
(pounds) and is flying at 7.90
miles/h
(miles per hour). What is the kinetic energy of the goose in joules?

Answers

Add 22.6+7.90 I hope this is right but may be wrong.
HIGH SCHOOL

Choose the statement that best describes the PbCl4 molecule in the gas phase. A. The molecule has a dipole moment.
B. The bond angles are all about 109.
C. The molecule is polar.
D. The bonds are non-polar.
E. More than one of these choices are correct.

Answers

Answer:

The correct answer is B. The bond angles are all about 109.

Explanation:

In bibliography or in the periodic table you can see that lead Pb has an electronic configuration of:

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p²

Valencia electrons are the electrons found in the last electronic layer (called valence orbitals). These electrons are what determine the ability of the atom to form bonds. When an element joins another, it does so through its valence electrons.  

In this case at the last level, level 6, there are 4 electrons, which are the valence electrons that will react with Cl. Since the compound PbCl₄ has 1 Pb and 4 Cl, this indicates that the 4 valence electrons of the lead Pb will react with each of the chlorine Cl. In this way they comply with the octet rule, which is the tendency of atoms to complete its energy level with eight electrons to achieve stability.

Then, around the central atom, Pb, there are 4 pairs of electrons (4 valence electrons of lead and 4 that are compatible with chlorine). Of these electron pairs, all are bonded. So the geometry is tetrahedral, with a link angle of 109.5 °.

Then, the correct answer is B. The bond angles are all about 109.

HIGH SCHOOL

The normal boiling point of methanol is 64.7°c and the molar enthalpy of vaporization if 71.8 kj/mol. the value of δs when 2.15 mol of ch3oh (l) vaporizes at 64.7°c is __________ j/k.

Answers

The value or amount of heat that is needed in order to vaporize the given amount of methanol (CH3OH) can be calculated through the equation,
    H = (n)(hf)

where H is the amount of heat
n is the given amount in mol, and 
hf is the molar heat of vaporization

Substituting the known values,

  H = (2.15 mol CH3OH)(71.8 kJ/mol)
  H = 154.37 kJ

ANSWER: 154.37 kJ
The molar enthalpy of vaporization is the amount of energy required to vaporize one mole of substance at a given temperature and pressure.

When we are given the amount of substance present, and the molar enthalpy of vaporization, we may simply use the formula:

ΔH = n * ΔH(vap) 

To find the enthalpy change occurring

ΔH = 2.15 * 71.8

The value of ΔH is 154.27 kJ.
MIDDLE SCHOOL

If two objects have the same masses, but different volumes, which one has the greater density? The one with less volume, or more volume?

Answers

Less volume has a greater density 
MIDDLE SCHOOL

Which is not a clue that a chemical change has taken place? A)changes color when heated

B)boils at 90°C

C)bubbles in water

D)disappears in acid

Answers

Boiled at 90 c* is a physical change



Answer:

answer B)

Explanation:

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