Question

Use the portion of the periodic table shown below to answer the questions. A portion of the first three columns of the periodic table is shown. Column one from top to bottom reads 11 sodium 22.990, 19 potassium 39.098, and 37 rubidium 85.468. Column two reads 12 magnesium 24.305, 20 calcium 40.078, and 38 strontium 87.62. Column three reads 21 scandium 44.956 and 39 yttrium 88.906. Part 1: Name two elements that have the same properties as calcium (Ca). (4 points) Part 2: Determine the number of protons, electrons, and neutrons present in an atom of sodium (Na). Explain how you determined your answer using complete sentences. (6 points)

Answer 1

I'm not sure about part 1, you may need to google it, but part two is 11 protons, 11 electrons and 12 neutrons. You can find protons and electrons by just looking at the atomic number, and you can find neutrons by subtracting the atomic number from the atomic mass.

Answer 2

Answer:

1) magnesium and strontium

2) number of protons = 11

number of electrons = 11

number of neutrons = 12

Explanation:

Part 1:  

Two elements that have the same properties as calcium are magnesium and strontium. Elements in the same group (represented as columns in periodic table) share the same properties because they have the same number of electrons in the outermost electron shell.

Part 2:

For sodium, from the periodic table we know:

atomic number: 11

atomic mass: 22.990 ≈ 23

The number of protons and electrons is indicated by atomic number, in this case sodium has 11 protons and electrons (remember that atoms of the elements are electrically neutral, then they have the same amount of protons and electrons).

The mass of the atom is almost concentrated in the atomic nucleus, then the atomic mass represents the amount of protons and neutrons combined. So,

number of neutrons = atomic mass - atomic number = 23 - 11 = 12