> How many valence electrons does a helium atom have?
The electron configuration of Helium is simply 1s2. We see that its outermost shell is the s shell and it contains 2 electrons, therefore the number of valence electrons is also 2.
> What is the formula of the ion formed when potassium achieves noble-gas electron configuration?
Potassium has a electron configuration of [Ar] 4s1. To have an electron configuration of only [Ar] which is a noble gas, the one electron from 4s1 should be removed, hence:
K+
What is the relationship between the molecular mass and the molar mass of a substance?
The molecular mass and the molar mass of a substance are numerically equivalent but measured in different units: amu and g/mol, respectively. The molecular mass in amu of a single molecule of a substance is the same as the molar mass in g/mol of one mole of that substance. This relationship is crucial for stoichiometric calculations in chemistry.
The molecular mass of a substance is the sum of the masses of all the atoms in a single molecule of that substance, measured in atomic mass units (amu). On the other hand, the molar mass of a substance is the mass of one mole of that substance, measured in grams per mole (g/mol). These two quantities have a direct relationship: for a given substance, the numerical value of the molecular mass in amu is equal to the numerical value of the molar mass in g/mol.
For example, the molecular mass of water (H2O) is approximately 18 amu (2(1) for hydrogen + 16 for oxygen), which means its molar mass is also 18 g/mol. To calculate the number of moles of a substance from its mass, we can use the equation: moles of solute (n) = mass of the solute (m) divided by the molar mass of the solute (M).
Understanding the relationship between molecular mass and molar mass is essential for converting between mass and moles of a substance, which is a fundamental concept in chemistry when dealing with reactions and stoichiometry.
A theory that has been proven true repeatedly over time and never disproven is called ??
The element chlorine is represented by the symbol ____. (Capitalization is important.)
The chemical symbol of the chlorine element is represented Cl.
What is the chemical element?A chemical element can be described as a species of atoms that have a given number of protons in their nuclei which includes a pure substance consisting only of that species.
The chemical elements cannot be further broken down into simpler substances, unlike chemical compounds, by any chemical reaction. The defining property of an element is the number of protons in the nucleus which is referred to as its atomic number.
Nearly all naturally occurring chemical elements occur on the Earth as compounds or mixtures. Air is primarily a mixture of nitrogen, oxygen, and argon, though it does contain compounds like carbon dioxide and water. A chemical symbol can bed described as a one- or two-letter designation of an element that has the first letter always capitalized.
The elements are organized in tabular form by increasing atomic numbers into rows called "periods" and into columns called "groups" that share physical and chemical properties. The modern periodic table summarizes various properties of the elements and the relationships between them.
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an ice cube and a scoop of table salt are left outside on a warm, sunny day. Explain why the ice cube melts and the salt does not
the reason why is that salt is a solid while ice is a liquid solid
or something like that but don't forget to put that it is a solid
A 0.465 g sample of an unknown compound occupies 245 ml at 298 k and 1.22 atm. what is the molar mass of the unknown compound? answer: a 0.465 g sample of an unknown compound occupies 245 ml at 298 k and 1.22 atm. what is the molar mass of the unknown compound? 26.3 g/mol 81.8 g/mol 33.9 g/mol 38.0 g/mol 12.2 g/mol
Determine the molar mass of an unknown compound by rearranging the ideal gas law to solve for the number of moles and then dividing the sample mass by the number of moles.
Explanation:You calculate the molar mass of a gas with the concept that at a consistent temperature and pressure, the molar volume of a gas is constant. The ideal gas law (PV = nRT), where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature, can be used under these conditions. Rearranging the equation and substituting molar mass for mass and number of moles gives you an equation to calculate molar mass.
First, convert volume from milliliters to liters, so 245 ml becomes 0.245 L. Using R as 0.0821 (atm L)/(mol K), the equation will yield the number of moles of the gas. Now, divide the given sample mass (0.465 g) by the calculated number of moles to obtain the molar mass. The correct choice among 26.3 g/mol, 81.8 g/mol, 33.9 g/mol, 38.0 g/mol, 12.2 g/mol is calculated through the steps described above.
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To what chemical reaction class does this reaction belong? 2 mg(s) + o2(g)2 mgo(s)
Under which circumstances is it wise to use a mixture of solvents to carry out a recrystallization
Name one physical property that could be used to distinguish chlorine from oxygen
What happens to the 6 carbon atoms of glucose when it is completely degraded?
Degradation means that a large molecule is broken down into simpler ones. In this case, glucose which has a chemical formula of C6H12O6 is broken down into simple parts.
Assuming that the reaction takes the form below, glucose is usually converted into 6 units of carbon dioxide CO2.
C6H12O6 + reactant --> 6CO2 + product
Final answer:
When glucose is completely degraded, its six carbon atoms combine with oxygen to form carbon dioxide during cellular respiration. The energy from glucose's chemical bonds is stored in energy-carrier molecules.
Explanation:
When glucose is completely degraded, all six carbon atoms combine with oxygen to form carbon dioxide. The process of glucose degradation occurs during cellular respiration, specifically through the Krebs Cycle. After two turns of the cycle, the original glucose molecule has been broken down completely, and the energy from its chemical bonds has been stored in energy-carrier molecules. In total, 16 energy-carrier molecules are produced.
Could you separate a mixture of salicylic acid and aspirin by acid-base extraction? briefly justify your answer.
What must be done to carbon dioxide gas to change it to a solid
The thing to be done to change carbon dioxide gas into a solid is to decrease the temperature till freezing point.
What is solid state?The condition of matter in which materials are not fluid but maintain their boundaries without support, with atoms or molecules maintaining fixed places in relation to one another and unable to move freely.
For changing the gaseous state into the solid state, we have to increase the pressure of gas so that the molecules of gas come close to each other or by decreasing the temperature of gas so that toms get freeze to not move freely.
Hence, by decreasing the temperature to freezing point, carbon dioxide gas will change into a solid.
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A 0.82 kg piece of wood floats in water but is found to sink in alcohol (sg=0.79), in which it has an apparent mass of 0.059 kg .
How many more h+ ions does a solution with a ph of 4 than a solution with a ph of 5?
Which subatomic particle did james chadwick discover? compare its mass to that of a proton. presi?
Calculate the mass of 2.60 mol of CH3OH(l)
What is the chemical equation for the vaporization of methanol?
The reaction of excess oxygen with an unknown volume of hydrogen at 200 c yields 3.22 l of steam. what is the volume of the hydrogen -pressure
The pressure of the system is approximately 19.64 atm.
To solve this problem, we can use the stoichiometry of the reaction between hydrogen and oxygen to form water vapor (steam). The balanced chemical equation for this reaction is:
2H2 + O2 → 2H2O
From the equation, we see that 2 moles of hydrogen react with 1 mole of oxygen to produce 2 moles of water vapor.
First, we need to determine the number of moles of water vapor produced using the ideal gas law:
PV = nRT
Where:
P = pressure
V = volume (in liters)
n = number of moles
R = ideal gas constant (0.0821 L·atm/(K·mol))
T = temperature (in Kelvin)
Given:
P = pressure of the system (which we need to find)
V = volume of steam produced = 3.22 L
T = temperature = 200°C = 200 + 273.15 = 473.15 K
Let's find the number of moles of water vapor first:
n = PV / RT
Substitute the given values:
n = (P * 3.22) / (0.0821 * 473.15)
Now, since the reaction is 2 moles of hydrogen to 2 moles of water vapor, we can say that the number of moles of water vapor produced is equal to the number of moles of hydrogen that reacted.
So, the number of moles of hydrogen reacting is also 'n'.
Now, 2 moles of hydrogen occupy 2 times the volume of the water vapor. So, the volume of hydrogen can be calculated as follows:
Volume of hydrogen = (2 * n) liters
Now, we need to find the pressure of the system. We can use the ideal gas law again:
P = nRT / V
Substitute the values:
P = (n * 0.0821 * 473.15) / (2 * n)
The 'n's cancel out, leaving us with:
P = 0.0821 * 473.15 / 2
Now, let's calculate this.
P = (0.0821 * 473.15) / 2
P ≈ 19.64 atm
So, the pressure of the system is approximately 19.64 atm.
Arrange the isotopes of sulfur and phosphorus in order of decreasing number of neutrons.
Rank the isotopes from most to fewest neutrons. To rank items as equivalent, overlap them.
Answer:
Rank of the isotopes from most to fewest neutrons:
S-36, P-35
P-33
P-32
S-32, P-31
Explanation:
The following options are missing:
S-36
P-35
S-32
P-33
P-32
P-31
Sulfur has 16 protons then S-36 has 36 - 16 = 20 neutrons and S-32 has 32 - 16 = 16 neutrons.
Phosphorus has 15 protons, then P-35 has 35 - 15 = 20 neutrons, P-33 has 33 - 15 = 18 neutrons, P-32 has 32 - 15 = 17 neutrons and P-31 has 31 - 15 = 16 neutrons.
What was Johann Dobereiner's contribution to the development of the periodic table?
He identified triads of elements that had similar properties.
What is the formula for sodium sulfate?
a. na(so)
b. naso
c. naso
d. na(so)?
What is the name of a list of elements arranged according to the ease with which they undergo certain chemical reactions?
An activity series is the list that ranks elements based on their chemical reactivity, with good reducing agents like alkali metals on top, and good oxidizing agents like halogens at the bottom. The periodic table also organizes elements by their properties but in a different format, where elements with similar properties are grouped into families.
The name of the list of elements arranged according to the ease with which they undergo chemical reactions is called an activity series. An activity series is a list of elements ordered not by their atomic mass or number, but by their chemical reactivity.
This list typically presents elements in decreasing order of their reactivity. Elements at the top of the list, such as the alkali metals, are known to be good reducing agents, which means they lose electrons easily. Conversely, elements at the bottom, such as the halogens, are good oxidizing agents, meaning they tend to gain electrons.
Periodic Table and Element Families
While the periodic table organizes elements by increasing atomic number and groups elements with similar properties together in columns, it is different from an activity series. For instance, elements within the same family like the alkali metals (Group 1) or alkaline earth metals (Group 2) have similar chemical properties.
The periodic table's design allows chemists and scientists to infer the chemical behavior of elements, and it was constructed by Mendeleev, who grouped elements with similar properties together, sometimes even adjusting the order of atomic masses.
If an automobile travels 215 mi with a gas mileage of 20.5 mi/gal , how many kilograms of co2 are produced? assume that the gasoline is composed of octane, c8h18(l), whose density is 0.69 g/ml.
Which could make up a solution?
Check all that apply.
A. A gas in a liquid
B. Two gases
C. Two solids
D. A solid in a liquid
In general, which properties are common to elements within a single group on the periodic table?
The balanced equation for combustion in an acetylene torch is shown below: 2C2H2 + 5O2 → 4CO2 + 2H2O The acetylene tank contains 35.0 mol C2H2, and the oxygen tank contains 84.0 mol O2. How many moles of CO2 are produced when 35.0 mol C2H2 react completely?
Final answer:
When 35.0 mol of C2H2 react completely according to the given equation, 70.0 mol of CO2 will be produced.
Explanation:
The student asked about the amount of CO2 produced when 35.0 mol C2H2 reacts completely, according to the balanced chemical equation provided for the combustion of acetylene (C2H2) in an acetylene torch: 2C2H2 + 5O2 → 4CO2 + 2H2O.
To find the amount of CO2 produced, we apply stoichiometry using the balanced equation. According to the equation, 2 moles of C2H2 produce 4 moles of CO2. Therefore, if 35.0 mol C2H2 react completely, the amount of CO2 produced can be calculated by setting up a ratio:
(35.0 mol C2H2) × (4 mol CO2 / 2 mol C2H2) = 70.0 mol CO2
Thus, 35.0 mol of C2H2 will produce 70.0 mol of CO2 when they react completely.
What do the letters mean in the brackets in the chemical reaction equation and how to balance them.
NaCl(s) + F2(g)
Final answer:
The letters in brackets in a chemical equation represent the physical states of substances; balancing a chemical equation requires the same number of each type of atom on both sides.
Explanation:
The letters in brackets like (s), (l), (g), and (aq) in a chemical reaction equation represent the physical states of the substances involved. (s) stands for solid, (l) for liquid, (g) for gas, and (aq) for aqueous solution, which means the substance is dissolved in water. To balance a chemical equation, you need to ensure that the number of atoms of each element is the same on both sides of the equation. For example, to balance Na (s) + Cl2 (g) → NaCl (s), we need to recognize that Cl2 is diatomic, and therefore the equation should be balanced as 2Na (s) + Cl2(g) → 2NaCl (s) to have equal numbers of sodium and chlorine atoms on both sides.
A mixture of helium, neon and argon gases have a total pressure of 790 mmhg. if there is 118.5 mmhg of argon, 474 mmhg of helium, what is the partial pressure of the neon gas?
Magnified we see that the carbon atom _______ in place. flashcard
Human activities can accelerate the process of
A) physical weathering
B) chemical weathering
C) both
Human activities can indeed accelerate the process of both physical and chemical weathering. Option C) is the correct answer.
Explanation:Physical weathering involves the degradation of rock through physical processes, such as freeze-thaw cycles or abrasion. Chemical weathering, on the other hand, involves the decomposition of rock through chemical reactions, such as oxidation and hydration.
Human activities, such as deforestation, mining, and construction, can accelerate these processes. For instance, the removal of trees (deforestation) can lead to more intense freeze-thaw cycles, accelerating physical weathering. Mining, meanwhile, exposes more rock to air and water, facilitating chemical reactions and thus speeding up chemical weathering.
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When two atoms collide, what determines whether they will react by transferring electrons or by sharing electrons?
Answer:
Explanation:
The covalent bond is the chemical bond between atoms where electrons are shared, forming a molecule. Covalent bonds are established between non-metallic elements, such as hydrogen H, oxygen O and chlorine Cl. These elements have many electrons in their outermost level (valence electrons) and have a tendency to gain electrons to acquire the stability of the electronic structure of noble gas.
An ionic bond is produced between metallic and non-metallic atoms, where electrons are completely transferred from one atom to another. During this process, one atom loses electrons and another one gains them, forming ions. Usually, the metal gives up its electrons forming a cation to the nonmetal element, which forms an anion.
So, a way to determine the type of bond will be knowing if the atoms are metallic or non-metallic.