Final answer:
An octet of electrons refers to an atom having eight valence electrons, providing stability similar to a noble gas. The octet rule primarily applies to main group nonmetals; however, exceptions like hydrogen that only needs two electrons and elements capable of expanded octets due to d orbitals exist.
Explanation:
The octet rule is a fundamental concept in chemistry that states atoms tend to bond in such a way that each atom has eight electrons in its valence shell, which provides stability and an electron configuration similar to that of noble gases. Elements strive to achieve an octet of electrons when forming chemical bonds, like in the case of carbon in carbon tetrachloride (CCl₄) where carbon forms four covalent bonds to obtain an octet.
Atoms from the main group elements, particularly nonmetals in the second period such as carbon (C), nitrogen (N), oxygen (O), and fluorine (F), typically follow this rule to form stable molecules. However, there are exceptions like hydrogen, which only requires two electrons to fill its valence shell. Moreover, expanded octet situations can occur with elements in the third period and beyond, where these atoms can hold more than eight valence electrons due to having available d orbitals, as in the case for phosphorus in phosphorous pentachloride (PCl₅).
What kind of chemical reaction does the chemical equation sodium + chlorine → sodium chloride represent? combustion decomposition single replacement synthesis NextReset
Which statement best describes the ideas of two scientists who studied properties of light? Newton and Maxwell had similar ideas about light being made of particles. Hertz extended Maxwell’s idea that light is produced by the interaction of electric and magnetic fields. Young supported Newton’s idea of the wave theory of light after observing light spread out in all directions. Huygens agreed with Maxwell that light has properties of both particles and waves.
Hertz extended Maxwell’s idea that light is produced by the interaction of electric and magnetic fields.
Answer:
Hertz extended Maxwell’s idea that light is produced by the interaction of electric and magnetic fields.
Explanation:
According to Maxwell electromagnetic waves propagated perpendicular to the direction of the oscillating mutually perpendicular electric and magnetic field. This electromagnetic disturbance could move through vacuum with the speed of light and had wave like properties.
Hertz designed experiments which proved Maxwell's idea: the electromagnetic nature of light.
Where does the energy that is released come from in a nuclear reaction in fission?
What are two things that you observed when you heated the mixture of tin and nitric acid over the Bunsen burner in the virtual lab, and why was it necessary to heat the mixture in order to determine the empirical formula?
only an odd number orbitals is possible for any electron sublevel
The claim that only an odd number of orbitals is possible for any electron sublevel is incorrect. There can be both odd and even numbers of orbitals, such as 1 orbital in the s subshell and 3 in the p subshell.
The statement that 'only an odd number of orbitals is possible for any electron sublevel' is not accurate according to quantum theory and the rules for assigning electrons to orbitals. In atomic structure, orbitals are spaces where electrons are likely to be found. These orbitals come in various shapes (s, p, d, f) and each type has a specific number of orbitals that can contain electrons. According to the Pauli Exclusion Principle, an orbital can hold a maximum of two electrons with opposite spins. Therefore, the s subshell has 1 orbital for 2 electrons, the p subshell contains 3 orbitals for up to 6 electrons, the d subshell consists of 5 orbitals for up to 10 electrons, and the f subshell has 7 orbitals for up to 14 electrons. This shows that the number of orbitals in a sublevel can be both even and odd.
For example, the electron configuration for fluorine is 1s² 2s² 2p⁵, illustrating how electrons fill into s and p orbitals. Furthermore, Hund's rules dictate that electrons are added to sublevels with every orbital singly occupied before any orbital is doubly occupied, reflecting the conservation of orbitals in quantum mechanics.
The alpha carbon is a chiral carbon atom, therefore, all alpha amino acids except one can exist in either of two enantiomers, called l or d amino acids, which are mirror images of each other. which amino acid id the exception
High temperatures increase reaction rates but lower rubisco selectivity for co2 versus o2. high leaf temperatures thus:
Which of the following animals would be found in the tropical rainforest? snake jaguar frog monkey bison
The scientist most often credited with the idea that a quantum of light (photon) can act as a particle is:
a. Schrödinger
b. de Broglie
c. Einstein
d. Heisenberg
Answer:
c. Einstein
Explanation:
Einstein is most credited with the idea that a quantum of light (photon) can act as a particle. He proposed that light behave as photons or quantum of energy and used it to explain the Photoelectric Effect for which he received the Noble prize. Prior to that light was believed to behave as a wave or electromagnetic radiation only. However, photoelectric effect showed that light has particle nature as well.
A __________ bond is a chemical bond between atoms with similar electronegativities; a sharing bond; valence electrons are shared.
Answer: This is known as non-polar covalent bond.
Explanation:
A covalent bond is formed when sharing of electrons takes place between the atoms forming a bond.
A polar covalent bond is formed when the atoms forming a bond have significant difference in electronegativities. This leads to the formation of poles in the atoms. For Example: HCl
A non-polar covalent bond is formed when the atoms forming a bond dpes not have significant difference in electronegativities or have similar electronegativity. For Example: [tex]H_2[/tex]
Hence, the bond is known as non-polar covalent bond.
A sample of argon gas has a volume of 5.40 l and a temperature of 15 °c. what is the final volume, in liters, of the gas if the temperature has been increased to 42 °c at constant pressure and amount of gas?
By applying Charles's law - V1/T1 = V2/T2 - and rearranging the formula as V2 = V1*(T2/T1), we find that the final volume of the argon gas when the temperature is raised to 42°C under constant pressure is 5.91 L.
Explanation:This question deals with the application of Charles's law, a fundamental concept in gas laws. Charles's law states that the volume of a gas is directly proportional to its temperature in Kelvin, assuming that pressure and the amount of gas remain constant.
First, convert the temperatures provided from Celsius to Kelvin. So, T1 = 15°C + 273 = 288 K and T2 = 42°C + 273 = 315 K. For the calculation, you would apply Charles's law formula - V1/T1 = V2/T2. Here, V1 is the initial volume (5.40 L), and T1 is the initial temperature in Kelvins (288 K). T2 is the final temperature in Kelvins (315 K), and we have to find V2 which is the final volume.
By rearranging the formula we get V2 = V1*(T2/T1) = 5.40 L * (315 K / 288 K) = 5.91 L.
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What is the product of (2.324X1.11 cm) expressed to the correct number of significant figures
What is the correct electron configuration of an ion of calcium, ca+2?
Answer:
Argon ( Ar)
Explanation:
A sample with ss = 40 and a variance of 8 has n = 5 scores.
a. True
b. False
The formula relating the sample variance, SS and n can be written as:
sample variance = SS / (n – 1)
so let us take that:
SS = 40
n = 5
calculate variance using the formula:
sample variance = 40 / (5 – 1)
sample variance = 10
Therefore the answer is:
False
How is a hydrogen bond different from the covalent bonds that connect each water molecule atoms? *?
Final answer:
A hydrogen bond is a weak attraction between the slightly positive hydrogen end of one polar molecule and the slightly negative end of another, while a covalent bond is a strong bond involving the sharing of electrons between atoms within a molecule. Hydrogen bonds are depicted with dashed lines and covalent bonds with solid lines in molecular diagrams. The hydrogen bond is much weaker than a covalent bond, requiring significantly less energy to break.
Explanation:
The key difference between a hydrogen bond and a covalent bond is the nature of the interactions that hold atoms or molecules together. In a water molecule ([tex]H_{2}[/tex]O), the oxygen and hydrogen atoms are held together by covalent bonds, which involve the sharing of electrons between atoms and are depicted by solid lines in molecular diagrams. These bonds are quite strong because they involve the sharing of electrons to create a stable electron configuration around each atom.
In contrast, a hydrogen bond is a weak attraction between the slightly positive hydrogen end of one polar molecule and the slightly negative end of another polar molecule, such as the oxygen atom in a different water molecule. This interaction is depicted by dashed lines in molecular diagrams and does not involve electron sharing; instead, it's a result of polar covalent bonds within the molecules that create slight positive and negative charges leading to an attraction between molecules. Because hydrogen bonds are between molecules, they are much weaker than the covalent bonds within molecules, requiring only about 10% of the energy to break compared to typical covalent bonds. This behavior illustrates why we can boil water, breaking the hydrogen bonds, without breaking the water molecules themselves, which would require disrupting their covalent bonds.
What indicates a chemical change?
A) Change from a liquid to a gas
B) Change in the amount of material
C) Change in the type of substance present
D) Change in the texture of a substance
Final answer:
The indication of a chemical change is the transformation of one substance into another, which is represented by option C) Change in the type of substance present. It involves observable signs like temperature change, color change, light production, gas formation, and precipitate formation.
Explanation:
What indicates a chemical change is a fundamental concept in understanding reactions and transformations in chemistry. The correct answer to the student's question is C) Change in the type of substance present. This occurs when a substance is turned into another as a result of a chemical reaction. Such changes are typically hard to reverse.
Observations that help indicate a chemical change include temperature changes, light given off, unexpected color changes, formation of bubbles that aren't due to boiling, and the formation of a precipitate. A change from a liquid to a gas or a change in texture, for example, can be attributed to physical changes, which do not alter the substance's molecular composition. The student's question relates to identifying chemical changes, focusing specifically on transformations that result in new substances with different chemical properties.
For each strong acid solutions, determine [h3o+],[oh−], and ph. 0.28 m hcl
For a 0.28M HCl solution, the concentration of H3O+ ions is assumed to be 0.28M due to the full ionization of strong acid. OH- concentration is obtained from the ion-product of water, and the pH is calculated from the negative log of H3O+ concentration.
Explanation:The concentration of hydronium ions [H3O+] in a 0.28M solution of HCl, a strong acid, can be assumed to be 0.28M. This is due to the complete ionization of a strong acid.
The OH- concentration [OH-] can be obtained from Kw, the ion-product of water (1x10^-14 at 25 degree Celsius). Knowing [H3O+] and Kb, we can calculate [OH-] using this relationship: [H3O+].[OH-] = Kw. The pH is then calculated from the [H3O+] using the relationship pH = -log([H3O+]).
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In the experiment involving hydrated copper sulfate, overheating causes a high calculated percent value for water. why is the high reading obtained?
Final answer:
Overheating in a hydration experiment of copper sulfate can cause decomposition of the substance, leading to an elevated calculation of water content due to additional weight loss incorrectly assumed to be water.
Explanation:
In the experiment involving hydrated copper sulfate, overheating can lead to a high calculated percent value for water because it may cause the copper sulfate to decompose further into copper oxide and sulfur dioxide, or lose additional bound water that is not part of the water of crystallisation. These additional losses are assumed to be water, resulting in an incorrect, elevated calculation of the water content. The precise weighing of starting and ending products is crucial to determine the amount of water in copper sulfate accurately.
Water solutions of ionic substances that conduct electricity are called
What is the mass number of an atom which contains 21 electrons, 21 protons, and 24 neutrons?
The mass number of the atom is 45.
Given:
An atom contains 21 electrons, 21 protons, and 24 neutrons.
To find:
The mass number of an atom.
Solution:
Number of protons in atom = p = 21
Number of neutrons in atom = n = 24
Mass number of an atom = A
[tex]A = p + n \\\\A = 21 + 24 \\\\A = 45[/tex]
The mass number of the atom is 45.
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In 1993 funding for a program increased by 0.16 billion dollars from the funding in 1992. In 1994, the increase was 1.14 billion dollars over the funding in 1993. For those three years the funding was 10.97 billion dollars. How much was funded in each of these three years?
Can you show me the equation?
Thanks
Hydrochloric acid reacts with calcium to form hydrogen and calcium chloride. If 100 grams of hydrochloric acid reacts with 100 grams of calcium, what is the limiting reactant? 2HCl + Ca → CaCl2 + H2
Answer:- The limiting reactant is HCl.
Explanation: The balanced equation is:
[tex]2HCl+Ca\rightarrow CaCl_2+H_2[/tex]
It's a stoichiometry problem. Masses of both the reactants are given and the questions asks to find out the limiting reactant.
We convert the given grams of each reactant to moles on dividing by its molar mass. Now, we can calculate the moles of any of the product on multiplying the moles of the reactant by mole ratio.
We do this starting with both the reactants and see which one gives less number of moles of the product. The limiting reactant is the one giving least number of moles of the product.
Molar mass of HCl is 36.46 gram per mol and that of Ca is 40.08 gram per mol.
Let's say we calculate the moles of hydrogen gas produced in the reaction. Mole ratio of [tex]H_2[/tex] to HCl is 1:2 and the mole ratio of [tex]H_2[/tex] to Ca is 1:1 .
The calculations are as shown below:
[tex]100gHCl(\frac{1molHCl}{36.46gHCl})(\frac{1molH_2}{2molHCl})[/tex]
= 1.37 mol [tex[H_2[/tex]
[tex]100gCa(\frac{1molCa}{40.08gCa})(\frac{1molH_2}{1molCa})[/tex]
= 2.50 mol [tex]H_2[/tex]
From above calculations, we get the least moles of hydrogen gas from 100 grams of HCl. So, the limiting reactant is HCl.
Part a a solution is made by mixing 9.00 mmol (millimoles) of ha and 3.00 mmol of the strong base. what is the resulting ph? express the ph numerically to two decimal places.
Assuming that the reaction is unimolecular on both reactant and product sides such that:
HA + OH- --> A- + H2O
Therefore the amount of A- left is:
mmol HA = 9.00 - 3.00 = 6.00
mmol A- = 3.00
pKa = - log Ka = 5.25
Calculating for pH:
pH = 5.25 + log 3.00/6.00
To calculate the resulting pH of a solution made by mixing 9.00 mmol of HA and 3.00 mmol of a strong base, you need to determine the concentrations of the acid and base, calculate the concentration of the resulting solution, find the pOH using the concentration of the conjugate base, and finally convert the pOH to pH.
Explanation:The pH of the solution can be calculated using the concentrations of the acid and the base. We can assume that the strong base reacts completely with the acid, so the resulting solution will contain only the conjugate base and water. Since we know the concentrations of the acid and base, we can determine the moles of each and calculate the new concentrations of the resulting solution. Finally, we can use the concentration of the conjugate base to find the pOH and then convert it to pH.
Given:
moles of HA = 9.00 mmol
moles of strong base = 3.00 mmol
Total volume of solution = unknown
Let's assume the total volume of the solution is 1 L for easier calculations. The concentration of the acid (HA) is 9.00 mmol / 1 L = 9.00 mM. The concentration of the conjugate base (A-) is also 9.00 mM since the acid and base react in a 1:1 ratio. The pOH of the solution can be calculated using the concentration of the base:
pOH = -log([OH-])
Since the concentration of the base is 9.00 mM, the pOH = -log(0.009) = 2.05
The pH of the solution can be calculated by subtracting the pOH from 14:
pH = 14 - pOH = 14 - 2.05 = 11.95
Therefore, the resulting pH of the solution is approximately 11.95.
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When using a light microscope, if you want the field of view to be larger, you would use
Answer:
The correct answer will be- low power objective lens.
Explanation:
In a light microscope, two types of lenses are used:
1. Ocular lens- the lens near to the eye of a viewer
2. Objective lens- The lens near the object.
Since the field of view decreases with increasing the objective power of the lens, therefore one wants to observe the large field of view than one should use low power of objective lens that is 4x.
Thus, the low power objective lens is the correct answer.
Which of the following is true of the three isotopes? Oxygen-16, Oxygen-17, Oxygen-18 *
They have a different number of protons.
They have the same atomic mass.
They have a different number of electrons.
They have different number of neutrons.
All isotopes of an element have the same number of protons and different numbers of neutrons. So, the isotopes Oxygen-16, Oxygen-17, and Oxygen-18 have different numbers of neutrons, not protons or electrons.
Explanation:The three isotopes, Oxygen-16, Oxygen-17, and Oxygen-18, are all isotopes of the element Oxygen. This means that they have the same number of protons, as the number of protons determines the identity of an element. In this case, Oxygen isotopes all have 8 protons. However, isotopes of the same element can have different numbers of neutrons. Indeed, Oxygen-16, Oxygen-17, and Oxygen-18 have 8, 9, and 10 neutrons respectively. They also have an identical number of electrons as protons to make the atom electrically neutral.
So, the statement 'They have different number of neutrons' is the correct one among the options.
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Which of the metals listed in the original list are less reactive than h2?
Copper, silver, mercury, and gold are less reactive than hydrogen as they are positioned at the bottom of the activity series and do not readily react with acids to produce hydrogen gas.
Explanation:The metals listed that are less reactive than hydrogen (H2) are those found at the bottom of the activity series. Specifically, these metals include copper (Cu), silver (Ag), mercury (Hg), and gold (Au). These metals do not react with acids to form hydrogen gas and hence are considered less reactive than hydrogen. Additionally, in the context of the electrochemical series, these metals are known as inert metals, indicating their low reactivity and their position at the very bottom of the activity series. Therefore, they do not readily corrode in the presence of dilute acids.
It's important to note that aside from basic trends, the exact order of reactivity of metals can be determined from the activity series or electrochemical series, where the lower a metal's position relative to hydrogen, the less reactive it is in comparison.
Given that you wished to use exactly 0.325 mole of nacl to prepare a 2.50 m nacl solution, how many milliliters of solution must you prepare
Why pressure increases as a gas is compressed into a smaller volume?
Part a in an effusion experiment, it was determined that nitrogen gas, n2, effused at a rate 1.812 times faster than an unknown gas. what is the molar mass of the unknown gas? express your answer to four significant figures and include the appropriate units.
The molar mass of the unknown gas is 92.0 g/mole
Explanation:
Part a in an effusion experiment, it was determined that nitrogen gas, n2, effused at a rate 1.812 times faster than an unknown gas. what is the molar mass of the unknown gas? express your answer to four significant figures and include the appropriate units.
The molar mass is the mass of a sample of that compound divided by the amount of substance in that sample in moles. Molar mass and molecular weight are often confused, but their values are very different.
Graham's law states the rate of diffusion or of effusion of a gas is inversely proportional to its molecular weight of the square root .
Graham's Law = rate of effusion of gas 2 / rate of effusion of gas 2
Graham's Law = square root (MM1 / MM2), where MM1 and MM2 are the molar masses of the gases.
Gas_2 = N_2, therefore
1.812 = √ (MM_1 / MM N_2)
1.812 = √ (MM_1 / 28.0)
1.812 = √ (MM_1 / √ 28.0 )
1.812 = √ (MM_1 / 5.29 )
1.812 x 5.29 = √ MM_1 = 9.59
MM_1 = 9.59^2 = 92.0 g/mole
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The hemoglobin content of blood is about 15.4 g/100ml blood. the molar mass of hemoglobin is about 64500 g/mol, and there are four iron (fe) atoms in a hemoglobin molecule. you may want to reference ( page ) section 3.1 while completing this problem. part a approximately how many fe atoms are present in the 6 l of blood in a typical adult?
The total number of iron (Fe) atoms in 6 L of blood in an adult human can be found by converting the volume of blood to the mass of hemoglobin, converting that to the moles of hemoglobin, and then considering how many Fe atoms that would be. It turns out to be approximately 3.44 x 10^23 Fe atoms.
Explanation:To approximate the number of iron (Fe) atoms in the 6 L of blood in an adult human, we must first convert the volume of blood to the mass of hemoglobin it contains. From the information provided, we know that blood contains about 15.4 g of hemoglobin per 100 ml. Therefore, in 6 L of blood, we have approximately 9240 g of hemoglobin, obtained by a simple conversion from liters to milliliters, then multiplying by the concentration of hemoglobin (15.4 g/100ml).
Next, we need to understand how many moles of hemoglobin that would be. The molar mass of hemoglobin is around 64500 g/mol. So, 9240 g of hemoglobin is about 0.143 mol.
Because there are four Fe atoms in each hemoglobin molecule, this is equivalent to 0.572 mol of Fe atoms. To calculate the actual number of Fe atoms, we multiply this by Avogadro's number (6.022 x 10^23 mol^-1), resulting in about 3.44 x 10^23 Fe atoms.
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