who was the first human in america

Find out how many valence electrons there are in total. Step 2: Write down the molecule's skeleton structure. Step 3: Each bond in the skeleton structure is formed by using two valence electrons.

First, the sum of the valencies of each atom determines the total number of valence electrons in the molecule.

The Lewis dot structure gains electrons (number of electrons added equals magnitude of negative charge) if the molecule is an anion.

A Lewis electron dot diagram, also known as an electron dot diagram, Lewis diagram, or Lewis structure, is a way to show the valence electrons in an atom by placing dots around the symbol for the element. The number of valence electrons in the atom is depicted by the diagram's number of dots. The atom symbol is surrounded by dots that represent the electrons in the outer shell. These symbols are referred to as Lewis symbols and electron dot symbols.

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According to the electronic configuration , gold and silver are inert metals and hence withstand the elements of the sea differently.

Electronic configuration is defined as the distribution of electrons which are present in an atom or molecule in atomic or molecular orbitals.It describes how each electron moves independently in an orbital.

Knowledge of electronic configuration is necessary for understanding the structure of periodic table.It helps in understanding the chemical properties of elements.

Elements undergo chemical reactions in order to achieve stability. Main group elements obey the octet rule in their electronic configuration while the transition elements follow the 18 electron rule.

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1. Determine the total number of valence electrons in the molecule or ion.

• Add together the valence electrons from each atom. (Recall that the number of valence electrons is indicated by the position of the element in the periodic table.)

•If the species is a polyatomic ion, remember to add or subtract the number of electrons necessary to give the total charge on the ion.

2. Arrange the atoms to show specific connections.

• When there is a central atom, it is usually the least electronegative element in the compound.

• Chemists usually list this central atom first in the chemical formula, which is another clue to the compound’s structure.

• Hydrogen and the halogens are almost always connected to only one other atom, so they are usually terminal rather than central.

3. Place a bonding pair of electrons between each pair of adjacent atoms to give a single bond.

• In H2O, for example, there is a bonding pair of electrons between oxygen and each hydrogen.

4. Beginning with the terminal atoms, add enough electrons to each atom to give each atom an octet (two for hydrogen).

• These electrons will usually be lone pairs.

5. If any electrons are left over, place them on the central atom.

• Some atoms are able to accommodate more than eight electrons.

6. If the central atom has fewer electrons than an octet, use lone pairs from terminal atoms to form multiple (double or triple) bonds to the central atom to achieve an octet.

• This will not change the number of electrons on the terminal atoms.

7. Final check

• Always make sure all valence electrons are accounted for and each atom has an octet of electrons except for hydrogen (with two electrons).

To prove the chemical formula of a compound using the Lewis structure, you need to follow these steps:

1. Draw the Lewis structure of the compound: Start by drawing the Lewis structure of the compound using the valence electrons of each atom. The valence electrons are the outermost electrons of an atom, which participate in chemical bonding. To determine the valence electrons of an atom, you can refer to its position in the periodic table.

2. Determine the number of electrons in the compound: Count the total number of valence electrons in the compound by adding up the valence electrons of each atom in the compound. This number is equal to the sum of the valence electrons of all the atoms in the compound.

3. Determine the number of electron pairs in the compound: Count the number of electron pairs in the compound by dividing the total number of valence electrons by 2. This gives you the number of electron pairs in the compound.

4. Determine the connectivity of the atoms: Identify the connectivity of the atoms in the compound by drawing the lines that connect the atoms in the Lewis structure. Each line represents a bond between the atoms.

5. Determine the formal charge of each atom: Calculate the formal charge of each atom in the compound by subtracting the number of lone pair electrons and half the number of bonding electrons from the total number of valence electrons for that atom. The formal charge of an atom should be as close to zero as possible.

6. Write the chemical formula: Write the chemical formula of the compound by using the symbol of each atom in the compound, along with its subscript, which corresponds to the number of atoms of each element present in the compound.

By following these steps, you can use the Lewis structure of a compound to prove its chemical formula.

Air escape from a tire when tire valve is opened because the pressure from the weight of the car is forcing the already pressurized air out .

When air is filled in tires, it get into more compact area than the outer atmosphere, therefore particles in tire are close to each other and exert pressure continuously on tire walls to get out of it. Thus, material of the tire need to be pressure resistant as much possible.

After opening the tire valve, air starts leaving with huge sound as strain outside the tire is weaker than that inside the tire. Molecules strike with the same force on larger area and pressure starts diminishing.

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Note: The question given on the portal is incomplete. Here is the complete question.

Question: Air leaves a tire when the tire valve is opened because

A. the pressure outside the tire is lower than the pressure inside the tire.

B. the pressure outside the tire is greater than the pressure inside the tire.

C. the temperature is higher outside the tire than inside the tire.

D. there are more gas particles outside the tire than inside the tire.

The reaction has a first order in Cl 2 and a second order in NO. The general order of reactions is 2+1 = 3.

We must ascertain the values of the exponents n, m, and p as well as the rate constant, k, in order to derive a rate law. The values of the coefficients required to formulate the rate law are available to us if the reaction orders for a reaction are provided.

The reaction's rate law is rate, starting from the slow step

k'[NOCl2][NO] - (1).

Fast step is used to determine the concentration of NOCl 2, which is an intermediate.

[NOCl 2]=K[NO][Cl2] - (2)

Substitute (2) in (1)

rate=k'K[NO][Cl2][NO]

Hence, rate =k[NO]2[Cl]

The reaction has a first order in Cl 2 and a second order in NO. The general order of reactions is 2+1=3

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1876.5J is the amount of heat released. Heat is the energy that moves through one body to another when temperatures are different.

Heat is the energy that moves through one body to another when temperatures are different. Heat passes from the hotter to the colder body when two bodies with differing temperatures are brought together.

By transitioning through one physical state (or phase) to another, such as from a phase from solid to liquid (melting), from such a solids to a vapour (sublimation), from either a liquid to a vapour (boiling), either from from solid form to another, a substance can absorb heat without increasing in temperature (usually called a crystalline transition).

q=m×c×ΔT

q=99.7632× 0.45×(64.4°C-22.6°C )    

q=99.7632× 0.45×41.8=1876.5J

Therefore, 1876.5J is the amount of heat released.

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The cost of 1 pound flask of mercury is $1.86. One of the most commonly used units for determining the mass or substance of an item or a body is the pound.

You really must understand what pounds signify when referring to weight. One of the most commonly used units for determining the mass or substance of an item or a body is the pound.

Scales are used in several ways to determine a body's weight or mass. To measure various items of various sizes, many sorts of scales are utilized. As the measure of an object's weight, pounds are used. In Britain, this style of measuring in pounds is typical.

cost of  76.00 pound flask of mercury =$142.00

cost of 1 pound flask of mercury=$142.00/  76.00 =$1.86

Therefore, the cost of 1 pound flask of mercury is $1.86.

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Answer:

The percentage of IF₅ (by mole) in the final product mixture will be 50%. This is determined by the stoichiometry of the reaction, the given molar mass of the reactants, and the ideal gas law.

Explanation:

Answer: +2

Explanation::)

Explanation:

The theoretical volume of ammonia that should be produced in the Haber process if we start with 5.0 L of nitrogen (N2) at standard temperature and pressure (STP) can be calculated as follows:

1 mole of N2 reacts with 3 moles of H2 to form 2 moles of NH3

Thus, the number of moles of N2 present can be calculated using the Ideal Gas Law:

PV = nRT

Where n is the number of moles of gas, R is the gas constant, T is the temperature in Kelvin, P is the pressure in atmospheres, and V is the volume in liters.

At STP (0°C and 1 atm), the volume of one mole of gas is 24.45 L.

Given 5.0 L of N2 at STP, the number of moles of N2 can be calculated as:

n = (PV)/RT = (1 atm)(5.0 L)/(0.0821 atmL/molK)(273 K) = 1.96 moles

The number of moles of NH3 produced can then be calculated as:

n = (2 moles of NH3)/(1 mole of N2) = 2 moles/1 mole = 2 moles

The volume of NH3 can be calculated as:

V = nRT/P = (2 moles)(0.0821 atmL/molK)(273 K)/(1 atm) = 44.8 L

So, the theoretical volume of ammonia (NH3) that should be produced if we start with 5.0 L of N2 at STP is 44.8 L.

5.6 mol N₂O is equal to 5.6 mol. (Note: The chemical formula N₂O already specifies the number of moles, so including "mol" after the number is redundant.) The answer, rounded to two significant figures, is 5.6 mol.

A mole is a unit of measurement in chemistry that represents an amount of a substance. One mole is defined as the amount of a substance that contains Avogadro's number of entities, where Avogadro's number is defined as 6.02214076 x 10²³ particles. This number is used to convert between mass, number of particles, and moles of a substance.

For example, one mole of a pure substance contains 6.022 x 10²³atoms, molecules, or ions, depending on the nature of the substance. The mole is a useful way to measure large amounts of chemical substances while avoiding the use of cumbersome numbers.

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The block on your desk given that it measures 3 cm by 4 cm by 6 cm and has a mass of 184.32 grams is made of marble

To know what the block is made of, we shall determine the density of the block. Details below:

Density = mass / volume

Density of block = 184.32 grams / 72 cm³

Density of block = 2.56 g/mL cm³

Thus, from the calculation made above and also considering the table of densities given, we can conclude that the block is made of marble.

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Missing part of question:

See attached photo

Taking into account the definition of significant figures, 8.4×10⁻² g  expressed using two significant figures is 8.4×10⁻² g

Significant figures are the digits of a number that are considered nonzero and have a real meaning and, therefore, provide some information.

To establish the significant figures you must bear in mind that:

Scientific notation is useful because it makes it easier to understand the value of measurements, especially when they have very large or very small values, and it helps to identify significant figures.

To express a measurement in scientific notation, the first significant figure is placed starting from the left in the units position, followed by the decimal point and the rest of the significant figures. The number obtained is then multiplied by the power of 10 needed to retrieve the original number.

Then, in this case, 8.4×10⁻² g  expressed using two significant figures is 8.4×10⁻² g, since 8 and 4 are the two significant digits.

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The enthalpy of this reaction is 1.48 kJ/mol.

The formula to calculate heat energy is

Q = m × c × ΔT

ΔT = T₂ - T₁

ΔT = T₂ - T₁ = 24.70 - 21.00 = 3.70 °C

Q = m × c × ΔT

Q = 191 × 4.184 × 3.70

Q = 2,956.83 J

Q = (2,956.83 ÷ 1,000) kJ

Q = 2.96 kJ

The enthalpy ΔH = Q ÷ n

ΔH = Q ÷ n

ΔH = 2.96 ÷ 2.00

ΔH = 1.48 kJ/mol

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Answer:

A

Explanation:

Na2SO4 +BaCl2 ____BaSO4+2NaCl

Some of the hazards that we should be aware of in the laboratory include the following: flammable substances, sharps (equipment that can cut or puncture skin) and fire. That is option A, B and E.

Laboratory hazards are those substances or equipments that are found in the laboratory which can cause harm to an individuals working in the laboratory.

Some of the hazards in the laboratory include chemical, biological, physical and radioactive hazards, as well as, musculoskeletal stresses.

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Some of the hazards to be aware of in this lab include;

A Laboratory hazard is anything that has the potential to cause damage or harm.

Chemical, biological, physical, radioactive, and other possible risks are all present for those working in a laboratory, in addition to musculoskeletal strains. Many employees are more likely to sustain injuries because they are not aware of the dangers that could exist at work.

Some laboratory hazards include:

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Na is for sodium and SO4 is sulfate...

Answer: The chemical compound name for Na₂SO₄ is Sodium Sulfate.

More molecules in a fixed volume means more pressure.

According to the context, the term may or may not include ions that meet this requirement. A molecule is a collection of two or more atoms held together by attractive forces known as chemical bonds.

Hence, it can be seen that an increase in the number of gas molecules, while container volume stays constant, increases pressure.

A decrease in container volume increases gas pressure. An increase in the temperature of a gas in a rigid container increases the pressure

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179.43 g/mol is the maximum amount of CO₂ which could be formed from 3.67 mol of C and 4.23 mol of O₂.

What is chemical reaction?

When molecules in a reactant undergo a chemical reaction, their bonds are broken, and molecules in the product undergo a similar process, new bonds are created, creating a new substance.

We are surrounded by chemical reactions on a daily basis, whether it be in our bodies as they process food or in the sun as they produce the light we see. Prior to starting with chemical reactions, it's crucial to understand physical and chemical changes.

C + O₂ → CO₂

carbon =  12.01g/mol

12.01  × 3.67

= 44.07 g/mol

O₂ = 32/mol

= 32 × 4.23

= 135.36 g/mol

44.07 g/mol + 135.36 g/mol

= 179.43 g/mol

Thus, 179.43 g/mol is the maximum amount of CO₂ which could be formed from 3.67 mol of C and 4.23 mol of O₂.

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State of emergency was proclaimed in Flint, the county seat of Genesee, by Michigan Governor Rick Snyder on January 5, 2016. Shortly after, President Barack Obama announced a federal state of emergency, approving further assistance from the Department of Homeland Security and the Federal Emergency Management Agency.

A public health emergency known as the Flint water crisis began in 2014 when the drinking water in Flint, Michigan was found to be tainted with lead and possibly Legionella bacteria. Flint switched its water source from treated Detroit Water and Sewerage Department water (obtained from Lake Huron and the Detroit River) to the Flint River in April 2014 due to a budget issue.

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This depends how much it costs per load of laundry.

For example:

If 1 load of laundry costs $2.50, this would mean that you need 10 quarters for one load. Multiply that by 10, and you get 100 quarters (the equivalent of $25).

Depending on how much the load costs, simply divide the price per load by .25 to get you total in quarters, then multiply it by 10 in this case.

The molar mass of H2O is 18.02 g/mol. Therefore, 122.4g is the mass of 6.80 moles H₂O. Water is a gaseous, liquid, as well as solid material.

Water is a gaseous, liquid, as well as solid material made of something like the chemical elements oxygen and hydrogen. It is one among the most abundant and necessary chemicals.

At room temp, it is a tasteless and odorless liquid with the critical capacity to dissolve several other compounds. Water's flexibility as either a solvent is critical to living creatures.

mass = moles × Molar mass

        = 6.80  × 18

         =122.4g

Therefore, 122.4g is the mass of 6.80 moles H₂O.

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The correct identification of the units is given below:

The SI units and the physical quantities they represent are the meter for length, the second for time, the kilogram for mass, the kelvin for temperature, the candela for light intensity, the ampere for current flow, and the mole for substance amount.

US customary units refer to the system of measures used in the US to measure objects. All other measures are conventional, including the gallon for volume, mile for length, pound for mass, and degree Fahrenheit for temperature.

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identify each unit as belonging to si units or us customary units. gallon. mile. meter. pound. kilogram. degrees farenheight. kelvin.

Cf cannot be a chemical symbol of an element. Therefore, option B is correct.

The term an element is defined as a substance that cannot be broken down into a simpler format. They are separate by a unequaled atomic number. The elements are formed by their atomic number in the periodic table, which highlights elements with similar properties.

Cf cannot be a chemical symbol of an element. CO is the symbol of element cobalt. B is the symbol of element boron and Cu is the symbol of an element copper.

Thus, option B is correct.

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Your question is incomplete, most probably your answer was

Which of the following cannot be the chemical symbol for an element

a. co

b. cf

c. b

d. cu

Answer:

The reactant that determines how much product can be made

Explanation:

The limiting reactant in a chemical reaction is the one that is consumed first and restricts the amount of product that may be produced (or limiting reagent).

Answer:

4.02 kJ

Explanation:

We must convert the answer to kJ 4023.25 J . 1kJ /1000 =4.02kJ

Dichotomous keys for the above can be:

A dichotomous key is a tool used to identify species of plants, animals, or other objects based on a series of choices between pairs of contrasting characters.

To create a dichotomous key, follow these steps:

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The IUPAC was founded in 1919 by academics and researchers who realized the need for chemical standardization. Therefore, in the below given ways molecules can be named.

The International Union of Pure as well as Applied Chemistry is abbreviated as IUPAC. It belongs to an international scientific publication with no government affiliation. The IUPAC works to develop chemistry by, among other things, establishing international quality standards for nomenclature, symbols, as well as units.

The IUPAC was founded in 1919 by academics and researchers who realized the need for chemical standardization. The International Union of Pharmaceutical Societies (IACS), the IUPAC's forerunner, convened in Paris in 1911 to discuss topics that needed to also be addressed.

CH[tex]_3[/tex] methane

CH[tex]_3[/tex]CH[tex]_3[/tex] ethane

CH[tex]_3[/tex]CH[tex]_2[/tex]CH[tex]_3[/tex] propane

Therefore, in the above given ways molecules can be named.

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A flask with a volume of 250.0 mL contains air with a density of 1.126 g/L. The mass of the air contained in the flask is 0.28 gram.

The density of a material is the measure of how tightly it is packed together. It is expressed as mass per unit volume. Density Symbol is D or

Formula Density = m/V, where is the density, m is the object's mass, and V is the object's volume.

Given:

Volume = 250.0 mL

Convert 250.0 mL in Liters :

250. 0 / 1000 = 0,25 L

Density = 1.126 g/L

Mass = g ?

Mass =  Density × Volume

Mass = 0.25 × 1.126

Mass = 0.28 gram

Thus, the mass of the air contained in the flask is 0.28 gram.

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Mass of 0.359 mol of KCI is calculated to be 26.79 g. Mass of a given chemical element or chemical compound (g) divided by the amount of substance (mol) is called molar mass.

Molar mass of a compound can be calculated by adding standard atomic masses of the constituent atoms.

The mass of 0.359 mol of KCI can be calculated by multiplying the number of moles by its molar mass:

mass = moles * molar mass

mass = 0.359 mol * 74.55 g/mol

mass = 26.79 g

So, the mass of 0.359 mol of KCI is 26.79 g.

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Answer: 26.79

Explanation: