Which electrons are removed from the outermost shell of a calcium atom, the atom becomes A)An anion that has a larger radius than the atom B)An anion that has a smaller radius than the atom C)a cation that has a larger radius than the atom D)a cation that has a smaller radius than the atom

QUESTION POSTED AT 13/02/2020 - 05:20 PM

Answered by admin AT 13/02/2020 - 05:20 PM

Answer is: D) a cation that has a smaller radius than the atom.

Atomic number of calcium is 20, it means that it has 20 protons and 20 electrons, so atom of calcium is neutral.  

When calcium lost two electrons, it will have 20 protons (positive charge) and 18 electrons (negative charge), which means it has two protons more and it has +2 oxidation number.


Electron configuration of calcium atom: ₂₀Ca 1s² 2s² 2p⁶ 3s² 3p⁶ 4s².

Electron configuration of calcium cation: ₂₀Ca²⁺ 1s² 2s² 2p⁶ 3s² 3p⁶.


Calcium cation is smaller than neutral calcium atoms, because when an electrons are lost, electron-electron repulsion decreases and the protons are better able to pull the remaining electrons towards the nucleus.

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Related questions

The correct answer is c. Energy processing from corn biofuels is not energy efficient.

Exellent!!!!!!!!!!!!!!

ANSWERED AT 28/02/2020 - 05:17 PM


QUESTION POSTED AT 28/02/2020 - 05:17 PM

Why do electrons in a copper penny not fly out?

Copper is a good conductor because, like other metals, it contains free electrons. Free electrons are also known as conduction electrons. Each copper atom provides a single free electron, so there are as many free electrons as atoms.

Free electron concentration in copper n = 8.5 × 1028 per m3


When a voltage is connected across a piece of copper, it pushes the free electrons so that they flow through the metal – that's an electric current.




Interactive graphic of electrical conduction
Interactive graphic of electrical conduction

Picture 3.4 Close the switch to apply voltage: electrons start to flow through. Increase the voltage and they drift faster.

About current

Notice that the electrons start to flow as soon as the switch is closed. The message to get them moving is instantaneous (in fact it travels close to the speed of light). However, the electrons themselves travel much more slowly. So how does the current come on everywhere as soon as the switch is closed?
It is because the free electrons are already spread through the wire. As soon as the switch is closed, there is a force on all the electrons, which gets them moving. It's a bit like a bicycle chain. As soon as you start pedalling, the back wheel starts to turn. The force on the back wheel is instantaneous even though the individual links are travelling at a visible speed. But because the links are already spread around the chain 'circuit' they all start to move at the same time.


Electron velocities

The animation above is slightly deceptive because it shows the electrons as being stationary when there is no voltage.
In reality, even when no current flows through a piece of copper, the free electrons are moving rapidly about. Their speed is about 106 m s-1; that's 3000 times the speed of sound in air! However, since they are moving at random, there is no net flow of electrons in any particular direction and so there is no current.

When a voltage is applied, the electrons gain an additional velocity, so that there is a net flow along the wire. This extra velocity is called their drift velocity. Here's a way to picture this:

ANSWERED AT 28/02/2020 - 05:05 PM


QUESTION POSTED AT 28/02/2020 - 05:05 PM

According to recent research, ice skaters are able to glide smoothly across the ice because A. ice is constantly subliming to form a layer of water vapor B. a thin, liquid-like layer of water covers the ice C. pressure from the skates raises the melting point of ice D. pressure from the skates lowers the melting point of ice

Answer:

B. A thin, liquid-like layer of water covers the ice

Explanation:

Hello,

Ice skaters are able to glide smoothly across the ice because a thin, liquid-like layer of water covers the ice, this is achieved due to the environmental conditions which allow the liquid water layer to coexist with the ice. Due to this fact, the liquid-like layer diminishes the friction coefficient between the ice skateboard and the ice allowing the slip to be carried out smoothly.

Best regards.

ANSWERED AT 28/02/2020 - 05:05 PM


QUESTION POSTED AT 28/02/2020 - 05:05 PM

What is the ph of a neutral solution at 25°c?

Answer:

pH = 7.00

Explanation:

In water at 25 °C,

K_{w} = [\text{H}_{3}\text{O}^{+}][\text{OH}^{-}] = 1.01 \times 10^{-14}\\

The solution is neutral, so [\text{H}_{3}\text{O}^{+}] = [\text{OH}^{-}]\\

[\text{H}_{3}\text{O}^{+}]^{2} = 1.01 \times 10^{-14}\\

[\text{H}_{3}\text{O}^{+}] = \sqrt{1.01 \times 10^{-14}} = 1.00 \times 10^{-7}

To get the pH, you take the negative logarithm of the hydronium ion concentration.

\text{pH} = -\log{( 1.00 \times 10^{-7})} = 7.00\\

ANSWERED AT 28/02/2020 - 05:03 PM


QUESTION POSTED AT 28/02/2020 - 05:03 PM

How many protons neutrons and electrons does nitrogen 14 have?

Many nitrogen atoms have seven neutrons (14-7 = 7). Some atoms of nitrogen, however, have eight electrons. They are atoms of N-15, an isotope of nitrogen. In a neutral atom, the number of protons must equal the number of electrons.

ANSWERED AT 28/02/2020 - 04:57 PM


QUESTION POSTED AT 28/02/2020 - 04:57 PM

What is the molarity of a solution of kno3 (molecular mass = 101 that contains 404 grams of kno3 in 2.00 liters of solution? a 1.00 b 2.00 c 0.500 d 4.00?

(1 mol KNO3/ 101 g KNO3)(404 g KNO3)= 4 moles
D

ANSWERED AT 28/02/2020 - 04:37 PM


QUESTION POSTED AT 28/02/2020 - 04:37 PM

A sample of hydrogen has an initial temperature of 50.° c. when the temperature is lowered to -5.0° c, the volume of hydrogen becomes 212 cm3 . what was the initial volume of the hydrogen in dm3?

Using the 
V1/T1=V2/T2
where
T1=50C= 323.15K
T2= -5C=268.15 K
V2= 212m^3
substitute the given values, we will get the initial volume
V1=V2T1/T2
V1= 255.48m^3

The initial volume is 255.48m^3




ANSWERED AT 28/02/2020 - 04:31 PM


QUESTION POSTED AT 28/02/2020 - 04:31 PM

Nuclear energy is produced when scientists force uranium (U) atoms to break apart. With this in mind, examine the list below. If scientists were to break apart each of the items on the list, which items would still be classified in the same way? Which items would be classified differently? • atoms • elements • compounds • molecules • matter

Answer:

Compound.

Explanation:

A compound is a made up of two or more than two different elements. It can be broken down into smaller molecules.Elements are combined to form a compound by chemical bonding like ionic bonding and covalent bonding.

Different compounds of different elements can be broken down into the chemical reaction called decomposition reaction. For example:

Using electrolysis, we can break down water into its elements hydrogen and oxygen.    

ANSWERED AT 28/02/2020 - 04:06 PM


QUESTION POSTED AT 28/02/2020 - 04:06 PM

An atom of an element has 28 innermost electrons and 7 outermost electrons. In which period of the Periodic Table is this element located? 1. 5 2. 2 3. 3 4. 4

Answer: The given element belongs to Period 4.

Explanation:

We are given:

Number of innermost electrons = 28

Number of outermost electrons = 7

Total number of electrons = 28 + 7 = 35

Electronic configuration is defined as the representation of electrons around the nucleus of an atom.

Number of electrons in an atom is determined by the atomic number of that atom.

The electronic configuration of the element having atomic number '35' is:  1s^22s^22p^63s^23p^64s^23d^{10}4p^5

To identify the period, we look at the highest occupied principle quantum number which is 'n'. Here, the value of highest occupied shell or 'n' is 4.

Hence, the given element belongs to Period 4.

ANSWERED AT 28/02/2020 - 03:57 PM


QUESTION POSTED AT 28/02/2020 - 03:57 PM

The modern model of the atom used today is the Plum Pudding model. true or false

That would be false.

ANSWERED AT 28/02/2020 - 03:42 PM


QUESTION POSTED AT 28/02/2020 - 03:42 PM

When you use the claw of a hammer to remove a nail , what type of simple machine are you using

You'd be using a wedge.

ANSWERED AT 28/02/2020 - 03:29 PM


QUESTION POSTED AT 28/02/2020 - 03:29 PM

Write the symbol for every chemical element that has atomic number less than 74 and atomic mass greater than 173.8u

You should be able to locate them on the periodic table as long as you know which part the atomic number is and which part the atomic mass is.

ANSWERED AT 28/02/2020 - 03:22 PM


QUESTION POSTED AT 28/02/2020 - 03:22 PM

A mole is the amount of a substance that contains as many particles as the number of atoms in 12 grams of what isotope?

The SI unit for amount of substance is the mole. It has the unit symbol mol. The proportionality constant is the inverse of the Avogadro constant. The mole is defined as the amount of substance that contains an equal number of elementary entities as there are atoms in 12g of the isotope carbon-12.

Hope This Helped! :3

ANSWERED AT 28/02/2020 - 02:51 PM


QUESTION POSTED AT 28/02/2020 - 02:51 PM

A mole is the amount of a substance that contains as many particles as the number of atoms in 12 grams of what isotope?

The 12C isotope.  Hope this helps.

ANSWERED AT 28/02/2020 - 02:51 PM


QUESTION POSTED AT 28/02/2020 - 02:51 PM

The specific heat of nickel is 0.44 J/g*⁰C. How much energy needed to change the temperature of 95.4g of nickel from 22⁰C to 32⁰C. Is the energy absorbed or released?

Answer : The amount of energy needed is, 419.76 J and the energy is absorbed.

Solution :

Formula used :

Q=m\times c\times \Delta T=m\times c\times (T_{final}-T_{initial})

where,

Q = heat gained or absorbed = ?

m = mass of nickel = 95.4 g

c = specific heat of nickel = 0.44J/g^oC      

\Delta T=\text{Change in temperature}  

T_{final} = final temperature = 32^oC

T_{initial} = initial temperature = 22^oC

Now put all the given values in the above formula, we get

Q=95.4g\times 0.44J/g^oC\times (32-22)^oC

Q=419.76J

The value of Q is positive that means energy is absorbed.

Therefore, the amount of energy needed is, 419.76 J and the energy is absorbed.

ANSWERED AT 28/02/2020 - 02:51 PM


QUESTION POSTED AT 28/02/2020 - 02:51 PM

In what phase of matter do particles fill the entire container in which their placed? A. Liquid B. Gas C. Solid D. Frozen

Answer:

gas

Explanation:

ANSWERED AT 28/02/2020 - 02:39 PM


QUESTION POSTED AT 28/02/2020 - 02:39 PM

Which of the phases below are NOT able to be compressed A. Solid only B. Liquid only C. Gas and Liquid D. Solid and liquid

Solid only, you can compress a liquid VERY little but it can be compressed.

ANSWERED AT 28/02/2020 - 02:31 PM


QUESTION POSTED AT 28/02/2020 - 02:31 PM

What is the name of this molecule? CH(Triple Bond)C-CH2-CH3

1 butyne should be your answer 

ANSWERED AT 28/02/2020 - 02:27 PM


QUESTION POSTED AT 28/02/2020 - 02:27 PM

How many electrons are needed to completely fill the second level energy? The third? The fourth?

The maximum number of electrons that an energy level can hold is determined from the formula 2n^2 equals the total number, where n is the energy level.  The first energy level holds 2*1^2=2 electrons while the second holds 2*2^2= 8 electrons.

ANSWERED AT 28/02/2020 - 02:04 PM


QUESTION POSTED AT 28/02/2020 - 02:04 PM

When 10g of calcium carbonate is heated,4.4g of carbon dioxide escape out. The amount of residue left is:

The dissociation of calcium carbonate, CaCO3, to simpler compounds can be expressed as,
                        CaCO3 --> CaO + CO2
The precipitate is CaO and its amount is calculated through the difference which will give us the answer of 5.6 g. 

ANSWERED AT 28/02/2020 - 01:38 PM


QUESTION POSTED AT 28/02/2020 - 01:38 PM

How many electrons can the n=4 shell hold? a. 8b.16c.32d.64?

Answer:

c.32

Explanation:

Hello,

In this case, it is possible to determine it by building the subshells organization for the first four shells as shown below:

1s^2\\2s^2\ 2p^6\\3s^2\ 3p^6\ 3d^{10}\\4s^2\ 4p^6\ 4d^{10}\ 4f^{14}

In such a way, counting the electrons at the n=4 shell, the result is 32 (2+6+10+14), so the answer is c.

Best regards.

ANSWERED AT 28/02/2020 - 01:30 PM


QUESTION POSTED AT 28/02/2020 - 01:30 PM