Question

1. fill in the blank: elements are made up of only one type of
2. why cant elements be broken down into simpler substances?
3. if an element has 3 energy levels, in which period is it found?

Explanation:

10. Step1: Recall the definition of elements

Elements are pure substances. By definition, they consist of only one type of atom.

11. Step1: Consider the nature of elements

Elements are the simplest form of matter in terms of chemical composition. They have a fixed atomic structure. Chemical reactions break bonds between atoms in compounds. But in elements, there are no such bonds to break to form simpler substances (as they are already in the simplest form for that particular element in terms of chemical identity).

12. Step1: Use the relationship between energy levels and periods

In the periodic table, the number of energy levels (electron shells) of an element's atoms is equal to the period number. If an element has 3 energy levels, then according to this rule.

Answer:

1. atom
2. Because they are the simplest form of matter in terms of chemical composition and have a fixed atomic structure with no bonds (within the element - in its pure form) to break to form simpler substances.
3. Period 3