Question

BRAINLIEST HELP ASAP

Answer 1

1- calcium and strontium, they are all alkaline earth metals
2- potassium has 19 p, 19 e, and 20. Electrons and protons are always the same as the atomic number (the number at the top) and neutrons is the protons minus the mass.
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Answer 2

Answer:

Part 1: Two elements with similar properties as magnesium are calcium, and strontium.

Part 2: The number of protons and electrons present in an atom of potassium (K) are 19, and the number of neutrons is 20.

Explanation:

Part 1

In the periodic table the elements are arranged so that those with similar chemical properties are located close to each other.

The elements are classified in order according to their atomic number, with a structure of eighteen columns, and seven rows. Rows are known as periods, and columns, as groups.

In a group, the chemical properties are very similar, because all the elements of the group have the same number of electrons in their last or last layers. Then, elements that have the same properties as magnesium (Mg) must belong to the same group. So two elements with similar properties as magnesium are calcium, and strontium.

Part 2

Each chemical element is characterized by the number of protons in its nucleus, which is called the atomic number Z. But in the nucleus of each element it is also possible to find neutrons, the number of which can vary. The atomic mass (A) is obtained by adding the number of protons and neutrons of a given nucleus.

The same chemical element may consist of different atoms, that is, their atomic numbers are the same, but the number of neutrons is different. These atoms are called element isotopes. the atomic mass of an element is the weighted average mass of its natural isotopes. Therefore, the atomic mass of an element is not an integer. The weighted average means that not all isotopes have the same percentage. In other words, the atomic masses of the chemical elements are usually calculated as the weighted average of the masses of the different isotopes of each element taking into account the relative abundance of each of them.

Then, for a potassium atom (K), the number of protons will be the value of the atomic number, being 19. As it is a neutral atom, the number of protons coincides with the number of electrons. The mass number has a value of  39.098≅39.  Knowing that the mass number is the sum of protons and neutrons, and knowing that the number of protons is 19, the number of neutrons will be:

neutrons=39-19

neutrons=20

So, the number of protons and electrons present in an atom of potassium (K) are 19, and the number of neutrons is 20.