Explanation:
Valence electrons is the number of electrons in the outermost shell of an atom. For the main group elements, the group number represents the number of valence electrons.
Beryllium
This belongs to the group 2 hence, it has valency of 2.
Nitrogen
This belongs to group 5, hence it has valency of 5.
Oxygen
This belongs to group 6, hence it has valency of 6.
Fluorine
This belongs to group 7, hence it has valency of 7.
Magnesium
This belongs to group 2, hence it has valency of 2.
Phosphorus
This belongs to group 5, hence it has valency of 5
Sulphur
This belongs to group 6, it has valency of 6
Chlorine
This belongs to group 7, it has valency of 7
Answer:
Beryllium: 2 valence electrons.
Nitrogen: 5 valence electrons.
Oxygen: 6 valence electrons.
Fluorine : 7 valence electrons.
Magnesium : 2 valence electrons.
Phosphorus : 5 valence electrons.
Sulphur : 6 valence electrons.
Chlorine : 7 valence electrons.
A 6.32L balloon is filled with air at 25.1°C. If the balloon is heated to 100 °C, what will be the new volume of the balloon
Answer:
7.90
Explanation:
Gay-Lussacs law states that P1/T1 = P2/T2
if:
P1 = 6.32
T1 (in Kelvins) = 25.1 + 273.1 =298.2
P2= ?
T2 = 100 + 273.1 = 373.1
so
6.32/298.2 = P2/373.1
P2 = 7.90
Two samples of sodium chloride with different masses were decomposed into their constituent elements. One sample produced 2.55 g of sodium and 3.93 g of chlorine. Being consistent with the law of constant composition, also called the law of definite proportions or law of definite composition, which set of masses could be the result of the decomposition of the other sample
Answer:
4.71 g of sodium and 7.25 g of chlorine
Explanation:
Note: The question is incomplete. the complete question is given below:
Two samples of sodium chloride with different masses were decomposed into their constituent elements. One sample produced 2.55 g of sodium and 3.93 g of chlorine. Being consistent with the law of constant composition, also called the law of definite proportions or law of definite composition, which set of masses could be the result of the decomposition of the other sample?
4.71 g of sodium and 3.30 g of chlorine
4.71 g of sodium and 7.25 g of chlorine
4.71 g of sodium and 1.31 g of chlorine
4.71 g of sodium and 13.7 g of chlorine
The law of definite proportions states that all pure samples of a particular chemical compound contain the same elements combined in the same proportion by mass.
This means that irrespective of the source of any sample of a pure chemical compound, the constituents elements are always combined in the same mass ratio.
In the first sample, the mass ratio of Sodium to chlorine is given below:
mass of sodium = 2.55 g
mass of chlorine = 3.93 g
mass ratio; sodium to chlorine = 2.55 / 3.93 = 0.65
From the set of masses give above, we can determine the result of the decomposition of the second sample.
4.71 g of sodium and 3.30 g of chlorine
mass ratio; sodium to chlorine = 4.71 / 3.30 = 1.43
4.71 g of sodium and 7.25 g of chlorine
mass ratio; sodium to chlorine = 4.71 / 7.25 = 0.65
4.71 g of sodium and 1.31 g of chlorine
mass ratio; sodium to chlorine = 4.71 / 1.31 = 3.59
4.71 g of sodium and 13.7 g of chlorine
mass ratio; sodium to chlorine = 4.71 / 13.7 = 0.34
From the results above, the correct set of masses for the second sample is 4.71 g of sodium and 7.25 g of chlorine
How do you figure out the # of
neutrons?
Answer:
Subtracting the number of protons from the atomic mass.
Answer:
Subtract Protons
Explanation:
Since the vast majority of atom's mass is found it's protons and neutrons, Subtracting the Number of Protons ( i.e. the atomic number ) from the atomic mass will give you the calculated number of neutrons in a atom,
a sample of fully saturated clay weighs 1350 g in its natural state and 975 g after drying. what is the natural water content of the soil
Answer:
The soil has a percentage of water by mass of 27.8 %.
Explanation:
Keeping in mind that
Mass of Clay = Mass of water + Mass of Dry Soilwe can calculate the mass of water:
1350 g = Mass of Water + 975 gMass of Water = 375 gWe can then calculate the mass percentage of water in the soil:
375 / 1350 * 100% = 27.8 %A particular term in an atom in which LS coupling is a good approximation splits into three levels, each having the same L and same S but different J. If the relative spacings between the levels are in the proportion 5:3, find L and S.
Answer:
Explanation:
From the information given;
Consider using Lande's Interval rule which can be expressed as:
[tex]\Delta E = E_{j+1} - E_jj \ = \alpha (j+1)[/tex]
here;
[tex]j+1[/tex] = highest level of j
and
[tex]\dfrac{\Delta E_1}{\Delta E_2} = \dfrac{(j+2)}{(j+1)}[/tex]
[tex]\dfrac{5}{3} = \dfrac{(j+2)}{(j+1)}[/tex]
[tex]5(j+1) = 3(j+2)[/tex]
[tex]5j+5 = 3j+6[/tex]
[tex]2j = 1\\ \\ j = \dfrac{1}{2}[/tex]
recall that:
[tex]j = |S-L| \ \to \ |S+L |[/tex]
So;
[tex]S-L = \dfrac{1}{2} --- (1)[/tex]; &
[tex]S+L = \dfrac{5}{2} --- (1)[/tex]
Using the elimination method, we have:
[tex]2S = \dfrac{6}{2}[/tex]
[tex]S = \dfrac{3}{2}[/tex]
Since [tex]S = \dfrac{3}{2}[/tex]; then from (1)
[tex]\dfrac{3}{2} -L = \dfrac{1}{2}[/tex]
[tex]L = \dfrac{2}{2}[/tex]
[tex]L = 1[/tex]
A student prepares a 100.0 mL solution using 44.7 grams of potassium nitrite. They then take 11.9 mL of this solution and dilute it to a final volume of 200.0 mL. How many grams of potassium nitrite are in a 19.7 mL sample of this final diluted solution?
Answer:
0.52 g of KNO₃ are contained in 19.7 mL of diluted solution.
Explanation:
We can work on this problem in Molarity cause it is more easy.
Molarity (mol/L) → moles of solute in 1L of solution.
100 mL of solution = 0.1 L
We determine moles of solute: 44.7 g . 1mol /101.1 g = 0.442 mol of KNO₃
Our main solution is 0.442 mol /0.1L = 4.42 M
We dilute: 4.42 M . (11.9mL / 200mL) = 0.263 M
That's concentration for the diluted solution.
M can be also read as mmol/mmL, so let's find out the mmoles
0.263 M . 19.7mL = 5.18 mmol
We convert the mmol to mg → 5.18 mmol . 101.1 mg / mmol = 523.7 mg
Let's convert mg to g → 523.7 mg . 1 g / 1000 mg = 0.52 g
How many moles are there in 3.4*10^26 moles of Ag
Answer:
It would be 151.832775 because one mole is 44.0095*3.45 i hope this helps!
Explanation:
Why is observational evidence important in an experiment?
Answer:
Observational evidence is essential for investigating the way disease affects populations, the patterns and distribution of risk within them, and the emergence of trends in health and disease over time.
Answer:
It tests a prediction It supports the results. It asks a testable question It predicts what will happen
Explanation:
To make the future development more eco-friendly and decrease water pollution from run-off, choose one of the following recommendations:
construct using only recycled materials
create gardens on all of the rooftops
install solar panels on every new building
Answer:
construct using only recycled materials ^^
Explanation:
Of the three layers of the biosphere, which one is inhabited by jellyfish?
Answer:
Hydrosphere
Explanation:
The biosphere simply refers to the zone of life found on earth. It refers to the portion of the earth inhabited by living things.
The biosphere is divided into three, namely; hydrosphere, atmosphere and lithosphere.
The atmosphere is simply the layer composed of air, the lithosphere is the solid part of the earth while the hydrosphere is the part composed of water.
Since jelly fish is an aquatic animal, it will certainly inhabit the hydrosphere. Hence the answer above.
How can simple machines make work easier?
A) By decreasing the effort needed to do the work
B) By adding more work on the object
C) By increasing the friction between the machine and the object
D) By removing the force of gravity on the object
Answer:
A) By decreasing the effort needed to do the work
Explanation:
The answer fam is....... A) By decreasing the effort needed to do the work
Hence the word simple Machine
If the caffeine concentration in a particular brand of soda is 2.57 mg/oz, drinking how many cans of soda would be lethal
The lethal dose and how ounces of soda in a can of soda is not given, however, the standard lethal dose and volume of soda are given as below:
Lethal dose: 10 gm of caffeine
The volume of soda per can = 12oz/can
Answer:
The correct answer is - 324.254 cans or round up to 325 cans. Ans.
Explanation:
Given:
2.57 mg caffeine / 1oz
12oz / 1can
Lethal dose: 10.0g or 10,000mg of caffeine
Solution:
Caffeine per soda can = (2.57 mg caffeine / 1oz) * (12oz / 1can) = 30.84 mg caffeine / 1can.
lethal dose would be in =
(10,000mg caffeine) * (1can / 30.84 mg caffeine) = 324.254 cans or round up to 325 cans. Ans.
compare and contrast synthesis reactions and decomposition reaction
Answer:
See explanation
Explanation:
Synthesis reaction and decomposition reactions are two opposing processes.
While a synthesis reaction has to do with the formation of a substance from its constituents, decomposition deals with the breakdown of a substance into its constituents.
While decomposition requires energy and is an endothermic process, synthesis is usually an exothermic process in which energy is given off as stable products are formed.
An unknown compound is processed using elemental analysis and found to contain 117.4g of platinum 28.91 carbon and 33.71g nitrogen how many moles of platinum are present
Answer:
1 mole of platinum
Explanation:
To obtain the number of mole(s) of platinum present, we need to determine the empirical formula for the compound.
The empirical formula for the compound can be obtained as follow:
Platinum (Pt) = 117.4 g
Carbon (C) = 28.91 g
Nitrogen (N) = 33.71 g
Divide by their molar mass
Pt = 117.4 / 195 = 0.602
C = 28.91 / 12 = 2.409
N = 33.71 / 14 = 2.408
Divide by the smallest
Pt = 0.602 / 0.602 = 1
C = 2.409 / 0.602 = 4
N = 2.408 / 0.602 = 4
The empirical formula for the compound is PtC₄N₄ => Pt(CN)₄
From the formula of the compound (i.e Pt(CN)₄), we can see clearly that the compound contains 1 mole of platinum.
Suppose you heat a metal object with a mass of 31.7 g to 96.5 oC and transfer it to a calorimeter containing 100.0 g of water at 17.3 oC. The water and metal reach a final temperature of 24.6 oC. What is the specific heat of the metal in J/g-oC?
Answer: The specific heat of the metal in [tex]1.34J/g^0C[/tex]
Explanation:
[tex]Q_{absorbed}=Q_{released}[/tex]
As we know that,
[tex]Q=m\times c\times \Delta T=m\times c\times (T_{final}-T_{initial})[/tex]
[tex]m_1\times c\times (T_{final}-T_1)=-[m_2\times c\times (T_{final}-T_2)][/tex]
where,
[tex]m_1[/tex] = mass of metal = 31.7 g
[tex]m_2[/tex] = mass of water = 100.0 g
[tex]T_{final}[/tex] = final temperature = [tex]24.6^oC[/tex]
[tex]T_1[/tex] = temperature of metal = [tex]96.5^oC[/tex]
[tex]T_2[/tex] = temperature of water = [tex]17.3^oC[/tex]
[tex]c_1[/tex] = specific heat of metal= ?
[tex]c_2[/tex] = specific heat of water = [tex]4.184J/g^0C[/tex]
Now put all the given values in equation (1), we get
[tex]m_1\times c_1\times (T_{final}-T_1)=-[m_2\times c_2\times (T_{final}-T_2)][/tex]
[tex]-(31.7\times c_1\times (24.6-96.5)^0C)=(100.0\times 4.184\times (24.6-17.3)][/tex]
[tex]c_1=1.34J/g^0C[/tex]
Therefore, the specific heat of the metal in [tex]1.34J/g^0C[/tex]
helppp nowwww please!!!!
Answer:
The sun will appear to rise and set more slowly
have a nice day! (^o^)
Electrons have what charge?
Answer:
negative charge
Explanation:
protons have a positive, nuetrons have a neutral charge , and electrons have a negative.
What kind of electrons
An attachment
A man receives a platinum ring from his fiancee. Before the wedding, he notices that the ring feels a little light for its size and decides to measure its density. He places the ring on a balance and finds that it has a mass of 3.15 grams. He then finds that the ring displaces 0.233 cm3 of water. Given that the density of pure platinum is 21.4 g/cm3, is this ring genuine
Answer:
The ring is probably not geniune.
Explanation:
To solve this problem we first need to calculate the density of the ring:
Density = mass / volumeThe mass is given by the problem, and we're able to assess the volume by keeping in mind Archimede's principle (the volume of water displaced by an object is equal to the object's volume).
Ring density = 3.15 g / 0.233 cm³ = 13.5 g/cm³Given that the ring density is significantly lower than the density of pure platinum, the ring is probably not geniune.
Uranus has a force of Gravity of 8.87 m/s^2. Sam has a MASS of 85 kg. What is his weight in Uranus? *
Answer:
Explanation:
Weight = mass x gravity
mass given = 85 kg
gravity = 8.87 m /s²
Weight = 85 x 8.87 = 753.95 N .
Weight on Uranus = 753.95 N .
When a precipitation reaction occurs, the ions that do not take part in the reaction are called
A.non participants
B.useless ions
C.independent variables
D.spectator ions
Answer:
D. spectator ions.
Explanation:
Hello!
In this case, when going over net ionic equations by which precipitation reactions are analyzed, we can consider the example of lead (II) nitrate with potassium iodide to yield insoluble lead (II) iodide and soluble potassium nitrate according to:
[tex]2KI(aq)+Pb(NO_3)_2(aq)\rightarrow PbI_2(s)+2KNO_3(aq)[/tex]
Whereas aqueous species remain in solution:
[tex]2K^+(aq)+2I^-(aq)+Pb^{2+}(aq)+2(NO_3)^-(aq)\rightarrow PbI_2(s)+2K^+(aq)+2(NO_3)^-(aq)[/tex]
It means that potassium and nitrate ions are spectator ions because they are not involved in the precipitation reaction, which is represented by the net ionic one:
[tex]2I^-(aq)+Pb^{2+}(aq)\rightarrow PbI_2(s)[/tex]
Thus, the answer to this question is D. spectator ions.
Best regards!
Please help quickly as possible thank you :)
Answer:
decreases a bit then stays constant
Explanation:
helppp nowwww plsssss!!
Answer:
The sun will appear to rise and set more slowly
have a nice day! (^o^)
Which change will produce a new substance?
Heating water until freezes
Cooling water until freezes
Burning a piece of wood
Dissolving sugar in water
helpppp nowwww plssss!!!
Answer: B
Explanation:
How does heat travel?
1. From cold things to hotter things
2. From hot things to colder things
3. Between things of the same temperature
Answer:
well heat travels by conduction, convection, and radiation but I think it's 2.
Explanation:
heat travels to colder things trying to make a balanced temperature for both of the objects.
4. Which employees should be aware of how to turn off power to a shop in an emergency?
Answer:
All employees should know how to work the system
100%
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6. What is the mass, in grams, of 1.92 moles of Ca(OH),?
Answer:
Mass = 142.25 g
Explanation:
Given data:
Mass of Ca(OH)₂ = ?
Number of moles of Ca(OH)₂ = 1.92 mol
Solution:
Formula:
Mass = number of moles × molar mass
Molar mass of Ca(OH)₂ = 74.09 g/mol
by putting values,
Mass = 1.92 mol × 74.09 g/mol
Mass = 142.25 g
Is caffeine additive?
Answer:
yes
Explanation:
yes
Combien y-a-t-il d'atomes grammes de zinc (Zn) dans 32,7 g de Zn?
How many grams of zinc (Zn) are in 32.7 g of Zn?
Answer:
32.7g
Explanation:
The mass of Zinc in the given substance is 32.7g.
Mass is the quantity of matter contained in a substance. The sum total of the amount of matter is the mass.
Since this problem gives us 32.7g of Zn then the substance will also contain 32.7g of Zinc.
Even when the Zinc is used in chemical reactions, we are expected to produce an equal amount of zinc as the product.
This way, mass is always conserved.