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In this video we’ll use the Periodic table and a few simple rules to find the protons, electrons, and neutrons for the element Calcium (Ca). From the Period. 5 Name: Calcium Analysis by Atomic Absorption Prestudy 1. 0.156 grams of CaCO3 is dissolved in aqueous HC1 and diluted to 250.00 mL in a volumetric flask. What is the ppm, mg Ca+2/L, of calcium ion in the final solution? A 10.0-mL volume of the above solution (C1) is. Standard atomic weight is used to give the value of the mean of the atomic masses in a mixture of isotopes in a given sample of an element. Atomic Mass of First 30 Elements. Given below is a table that lists the first 30 elements based on atomic number and their corresponding atomic mass. Calcium (Ca) is No. 20 in the periodic table of the elements, appearing just below magnesium in the same column (Group IIA) as the other alkaline earth metals (a group of metals that are more.

1. Atomic No. Of Potassium
2. Atomic No Of Calcium Oxide
3. Atomic No Of Calcium Phosphate

Click a column header, such as Name, to sort the table by that item.
SEENotes at the bottom of the Table.

Notes:
• Density of elements with boiling points below 0°C is given in g/l. In a sorted list, these elements are shown before other elements that have boiling points >0°C.
• Earth crust composition average values are from a report by F. W. Clarke and H. S. Washington, 1924. Elemental composition of crustal rocks differ between different localities (see article).
• Group: There are only 18 groups in the periodic table that constitute the columns of the table. Lanthanoids and Actinoids are numbered as 101 and 102 to separate them in sorting by group.
• The elements marked with an asterisk (in the 2nd column) have no stable nuclides. For these elements the weight value shown represents the mass number of the longest-lived isotope of the element.

Abbreviations and Definitions:

No. - Atomic Number; M.P. - melting point; B.P. - boiling point

Atomic number: The number of protons in an atom. Each element is uniquely defined by its atomic number.

Atomic mass: The mass of an atom is primarily determined by the number of protons and neutrons in its nucleus. Atomic mass is measured in Atomic Mass Units (amu) which are scaled relative to carbon, ¹²C, that is taken as a standard element with an atomic mass of 12. This isotope of carbon has 6 protons and 6 neutrons. Thus, each proton and neutron has a mass of about 1 amu.

Isotope: Atoms of the same element with the same atomic number, but different number of neutrons. Isotope of an element is defined by the sum of the number of protons and neutrons in its nucleus. Elements have more than one isotope with varying numbers of neutrons. For example, there are two common isotopes of carbon, ¹²C and ¹³C which have 6 and 7 neutrons respectively. The abundances of different isotopes of elements vary in nature depending on the source of materials. For relative abundances of isotopes in nature see reference on Atomic Weights and Isotopic Compositions.

Atomic weight: Atomic weight values represent weighted average of the masses of all naturally occurring isotopes of an element. The values shown here are based on the IUPAC Commission determinations (Pure Appl. Chem. 73:667-683, 2001). The elements marked with an asterisk have no stable nuclides. For these elements the weight value shown represents the mass number of the longest-lived isotope of the element.

Electron configuration: See next page for explanation of electron configuration of atoms.

Ionization energy (IE): The energy required to remove the outermost electron from an atom or a positive ion in its ground level. The table lists only the first IE in eV units. To convert to kJ/mol multiply by 96.4869. Reference: NIST Reference Table on Ground states and ionization energies for the neutral atoms. IE decreases going down a column of the periodic table, and increases from left to right in a row. Thus, alkali metals have the lowest IE in a period and Rare gases have the highest.

Other resources related to the Periodic Table

• Chemical Evolution of the Universe
  

What is the mass number of a Calcium atom if it has 20 neutrons?

1 Answer

Explanation:

First thing first, you need to make sure that you have a clear understanding of what mass number actually is.

As you know, the nucleus of an atom contains protons, which are positively charged particles, and neutrons, which are neutral particles.

An atom's mass number will always tell you how many protons and neutrons its nucleus contains.

Atomic No. Of Potassium

#color(blue)('mass number' = 'no. of protons' + 'no. of neutrons')#

Atomic No Of Calcium Oxide

In your case, you know that an atom of calcium, #'Ca'#, has #20#neutrons in its nucleus.

This means that in order to get its mass number, all you need to know is how many protons are found in its nucleus.

As you know, the number of protons an atom contains in its nucleus is given by that atom's atomic number. A quick look in the periodic table will reveal that calcium has an atomic number equal to #20#.

Now, in order for an atom to be an atom of calcium, it Must contain #20# protons in its nucleus. Always. The number of neutrons can vary, but the number of protons must always be equal to #20# for a calcium isotope.

Therefore, the mass number of this calcium isotope will be

#'mass number' = A = '20 protons' + '20 neutrons' = 40#

Atomic No Of Calcium Phosphate

You are dealing with the calcium-40 isotope, #'_20^40'Ca'#.

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