The density of Ca will be between that of Mg and Sr
Explanation:
Ca, Mg and Sr are group II elements. They are called alkali earth metals. The correct order of the elements in this group are: Be, Mg, Ca, Sr, Ba and Ra.
Density is an intensive property of matter which describes the amount of matter(mass) per volume of a substance.
- Density varies proportionally with mass. The higher the mass, the higher its density.
- On the periodic table, atomic mass which the number of protons and neutrons in the nucleus of an atom increases down the group.
- This implies a progradation in the value of density down the group. Therefore one expects that the value of density of Ca will fall between that of Mg and Sr. It cannot be more than 2.6g/cm³ nor less than 1.74g/cm³.
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Answer:
Atomic Particles
Atoms consist of three basic particles: protons, electrons, and neutrons. The nucleus (center) of the atom contains the protons (positively charged) and the neutrons (no charge). The outermost regions of the atom are called electron shells and contain the electrons (negatively charged).
Answer:
The atomic mass of phosphorus is 29.864 amu.
Explanation:
Given data:
Atomic mass of phosphorus = ?
Percent abundance of P-29 = 35.5%
percent abundance of P-30 = 42.6%
Percent abundance of P-31 = 21.9%
Solution:
Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass) + (abundance of 3rd isotope × its atomic mass / 100
Average atomic mass = (29×35.5)+(30×42.6) + (31×21.9) /100
Average atomic mass = 1029.5 + 1278 + 678.9/ 100
Average atomic mass = 2986.4 / 100
Average atomic mass = 29.864 amu.
The atomic mass of phosphorus is 29.864 amu.
Answer: The mass of 
molecules of phosphorus pentoxide is 20.5 g
Explanation:
According to avogadro's law, 1 mole of every substance weighs equal to the molecular mass and contains avogadro's number 
of particles.
To calculate the moles, we use the equation:
1 mole of 
weigh = 283.9 g
Thus 0.0772 moles of weigh = 
Thus the mass of molecules of phosphorus pentoxide is 20.5 g
