What is the total number of electrons in an atom of an element with an atomic number of 18 and a mass number
of 40?
a. 58
c. 22
b. 18
d. 40
Answer:
18
Explanation:
In neutral atom protons and electrons are equal in number as it atomic number or proton number is 18 so electrons are also 18
The total number of electrons in an atom of an element with an atomic number of 18 and a mass number of 40 is 18.
What are the difference between atomic number and atomic mass ?Atomic mass can be defined as the total number of neutrons and protons located in nucleus of an element while atomic number is the number of protons present in the nucleus of element.
Atomic mass can be defined as the average weight of an element where as the atomic number is the total number of protons present in the nucleus; Atomic mass have the symbol A while atomic number have the symbol the letter Z.
Different isotopes of an element are differentiated by atomic mass is while isotopes share the same atomic number, in neutral atom protons and electrons are equal to atomic number or proton number is 18 and electrons are also 18
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By examining the diagram, which of the following is NOT needed for photosynthesis:
O sunlight
O carbon dioxide
O water
oxygen
The
the surface area of the reactants, the faster the reaction rate.
A. greater
B. lesser
where information about each element is located
Answer:
On the pereiodic table.
Explanation:
A group of tourists were on an outing when they noticed that precipitation began to fall. The air temperature was 32 degree Fahrenheit. What type of precipitation did they most likely see?
Answer:
The correct answer is - rain.
Explanation:
At 32 degrees c or zero degrees Celsius, droplets of water in the atmosphere do not freeze as it is not the temperature at which water freezes but it is the temperature at which ice melts.
At this temperature the water changes its state, below 32 degrees Fahrenheit the water freezes but in the atmosphere, it not freezes necessarily and remains in the liquid state and called super-cooled liquid or water. Above this temperature, water in liquid state.
Thus, the precipitation is in the form of rain.
Could a person at the South Pole see the North Star? Explain.
Answer:
Yes
Explanation:
Because yes
Answer:
Yes, North is a direction and the south pole is a place so yes you can see the north star from the south pole
Explanation:
Which of the following has the larger atomic radius?
O Cs
O Ca
O Li
O Ba
Hope it helps
The cause of the phases of the moon Is a cycle that is close to - long
Answer: 28 days.
Hope this helps...... Stay safe and have a Merry Christmas!!!!!!!!! :D
What is the percentage composition of each element in carbon dioxide, CO2? Remember percent composition is based on mass. (Show your calculations for full credit.)
%C = 27.3%
%O=72.7%
Further explanationProust states the Comparative Law that compounds are formed from elements with the same Mass Comparison, so that compounds have a fixed composition of elements
The empirical formula is the mole ratio of compounds forming elements.
MW CO₂ : 44 g/mol
Ar C = 12 g/mol
Ar O = 16
%C[tex]\tt \dfrac{12}{44}\times 100\%=27.3\%[/tex]
%O[tex]\tt \dfrac{2.16}{44}\times 100\%=72.7\%[/tex]
Which is the correct Lewis dot structure for BeH2 ?
The correct Lewis dot structure for [tex]BeH_2[/tex] is Be : H : H
What does the Lewis dot structure show?The Lewis dot structure shows the valence electrons as dots. The valence electrons of beryllium are shown as 2 dots on the left side of the atom.
The central atom, beryllium, has 2 valence electrons where each hydrogen atom has 1 valence electron. To form a stable molecule, beryllium shares its 2 valence electrons with the 2 hydrogen atoms, each of which shares its 1 valence electron with beryllium which gives each atom a full outer shell of electrons.
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atoms are so small that approximately _________ of them can fit on the head of a needle?
Answer:
5 million
Explanation:
I need help please and thank you
Answer:
ooooooooooooooooooh i dont know this one
Explanation:
im not good a math at all
A car travels 65 miles in 1 hour. What is the average speed of the car?
I need to someone to explain the whole being of Chemistry. I do not understand a single thing, nothing makes sense to me. Literally, I'm going to fail this class because I do NOT understand a single thing taught to me. Maybe it's because I was mistakenly put into Chemistry Pre AP instead of on level but it's so hard and- I just do not get it.
Answer:
Explanation:
In Pre-AP Chemistry, the development of models to explain their macroscopic observations is a primary means through which students develop an understanding of the molecular world.
You will be forced to think and apply concepts to new situations, and even derive your own theories from application. This is excellent preparation for the higher levels of thinking required in college.
Chemistry, the science that deals with the properties, composition, and structure of substances (defined as elements and compounds), the transformations they undergo, and the energy that is released or absorbed during these processes.
0.45 g of hydrated sodium carbonate crystals were heated until 3.87 of anhydrous power remained.
How many moles of water are there in one mole of hydrated salt?
Formula of hydrated sodium carbonate : Na₂CO₃.10H₂O, so moles of water in one mole of hydrated salt = 10
Further explanationHydrate is a compound that binds water (H₂O), usually in the form of crystals/ solids
If these compounds are dissolved in water or heated, the hydrates can decompose:
Example: X.YH₂O (s) → X (aq) + YH₂O (l)
The formula for the hydrated compound contains: YH2O
The mole ratio shows the ratio of the coefficients of the hydrate compound
10.45 hydrated sodium carbonate(Na₂CO₃.xH₂O) were heated until 3.87 of 3.87of anhydrous (Na₂CO₃) remained, so
mass H₂O released :
[tex]\tt 10.45-3.87=6.58~g[/tex]
mass Na₂CO₃ = 3.87 g
mol ratio Na₂CO₃(MW= g/mol) : H₂O(MW=18 g/mol) =
[tex]\tt \dfrac{3.87}{105,9888}\div \dfrac{6.58}{18}=0.0365\div 0.3655=1\div 10[/tex]
A neutral atom of beryllium (Be) has an average mass of 9 amu and 4 electrons. How many neutrons does it have?
13
5
9
4
Answer:
It has 5 neutrons
Explanation:
The fact that it is a neutral atom tells us that the number of electrons and protons is the same:
The problem tells us there are 4 electrons, thus there are 4 protons.The average mass of an atom is the sum of the number of protons and the number of neutrons:
Mass = # Protons + # NeutronsWith the above information in mind we can calculate the number of neutrons:
9 amu = 4 Protons + # Neutrons# Neurons = 5 NeutronsAll of the alkaline earth metals are similar in that – they are all artificially made elements they all have similar atomic weights. they all have the same ionic charge. they all show variable valences.
Answer:
they all have the same ionic charge.
Explanation:
Alkaline earth metals are group 2 metals on the periodic table. They are divalent elements because they have two valence electrons and ionize by donating these two valence electrons. Elements in this group have the same numbers of electrons in their outermost shell of their atoms. i.e. they all have the same number of valence electrons and ionic charge.
Which best explains the difference between a monomer and a polymer?
A monomer is larger than a polymer.
A monomer contains carbon and a polymer does not.
A polymer contains carbon and a monomer does not.
A polymer is larger than a monomer.
The difference between the monomer and a polymer should be that monomer should be larger than a polymer.
Difference of monomer and a polymer?The monomer represent the molecule type where it has the capability for chemically the bond along with the other molecules with respect to the long chain. While the polymer should represent the chain of the non-specified the no of monomers.
Also, it represent the building blocks of polymers that contain more complex type of molecules
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Answer:
A
Explanation:
QUESTION 10
Which of the following is not a characteristic of ionic compounds?
A. Contains metals and non metals
B. Ions form a crystal structure
C. Conducts electricity in the solid state
D. High melting point
Answer: C. Conducts electricity in the solid state
Explanation:
Which model best represents a pattern?
Antenne UHF
Chaum
RTG
Master
Antenne
grand gain
DAN
REMS
RAD
SAM
Chemin
What is an example for "chemical equations"?
Answer:
A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and formulae, wherein the reactant entities are given on the left-hand side and the product entities on the right-hand side.
Explanation:
Which sentence best explains the relationship between pressure and the
solubility of a gas?
A. The greater the pressure, the more gas that will dissolve.
B. Solubility increases with pressure for some gases but not others.
C. The lower the pressure, the more gas that will dissolve.
D. Pressure has no effect on the solubility of gases.
Answer: A. The greater the pressure, the more of gas that will dissolve.
Explanation: Increasing pressure increases the solubility of gases. It has little effect on the solubility of liquids and solids.
how much heat is absorbed when 15.0 g of liquid water is heated until the temperature increases by 16.0.
how does atomic radius affect coulombic attraction?
A beaker containing 6.32 moles of PBr3, contains___
molecules of PBrz.
A) 1712.7
B) 3.1 x 10^24
C) 3.8 x 10^24
D) 271
Answer:
3.8 x 10²⁴molecules
Explanation:
Given parameters:
Number of moles = 6.32moles
Unknown:
Number of molecules = ?
Solution:
The number of moles can be used to derive the number of molecules found within a substance.
Now,
1 mole of substance contains 6.02 x 10²³ molecules
6.32 mole of PBr₃ will contain 6.32 x 6.02 x 10²³ = 3.8 x 10²⁴molecules
How many liters will 90.0 grams of xenon gas (Xe) occupy at STP?
HELP PLEASE
Answer:
22.4L
Explanation:
not sure if its totally correct but I tried
How much oxygen (O) is in 5.41 × 106 atoms of oxygen
Answer:
They show you how to do it sweetie
Explanation:
123456789 Common math
is bird seed homogeneous or heterogeneous
Answer:
heterogeneous
In order to give birds a varied and balanced diet, commercial bird seed blends typically include a range of seeds, grains, and other substances. As a result, bird seed is frequently categorised as a heterogeneous blend.
A seed is referred to as homogenous if its genetic makeup, size, shape, and other traits are all consistent. To guarantee consistency in the ensuing plants, these seeds are typically created through controlled breeding or genetic manipulation. A heterogeneous seed, on the other hand, is one that varies in genetic makeup, size, shape, and attributes. These seeds frequently result from cross-pollination or natural pollination between various species or kinds.
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Hair is composed of a protein called cellulose
O
True
O False
Answer:True
Explanation:
Iv done this before
True or False: Sulfur by itself isn't too bad, it's when it reacts with other elements that it can become dangerous
Answer:sulfer by itself is not pleasant and it can be dangerous by itself but in large amounts.
Explanation:
Answer:
True.
Explanation:
Also did you know that it is combined with chlorine that it becomes salt? Cool right? Two deadly things combining to become a condiment