Question

1.. The region in which an electron is most likely to be found is called a(an) ____________________.

2. An atom in which an electron has moved to a higher energy level is in a(an) ____________________ state.

3. When Mendeleev organized elements in his periodic table in order of increasing mass, elements with similar properties were in the same ____________________.

4. Mendeleev’s periodic table was useful because it enabled scientists to predict properties of unknown ____________________.

Answer 1

1. The region in which an electron is most likely to be found is called an orbital.

2. An atom in which an electron has moved to a higher energy level is in an excited state.

3. When Mendeleev organized elements in his periodic table in order of increasing mass, elements with similar properties were in the same column. 

4. Mendeleev’s periodic table was useful because it enabled scientists to predict properties of unknown elements.

Answer 2

1. The region in which an electron is most likely to be found is called an $\boxed{\text{orbital}}$.

2. An atom in which an electron has moved to a higher energy level is in $\boxed{\text{excited}}$ state.

3. When Mendeleev organized elements in his periodic table in order of increasing mass, elements with similar properties were in the same $\boxed{\text{columns}}$.

4. Mendeleev’s periodic table was useful because it enabled scientists to predict the properties of the unknown $\boxed{\text{elements}}$.

Further Explanation:

1. Electrons are the subatomic particles that carry a negative charge on them. These revolve around the atomic nucleus on definite circular paths which are known as orbits. The region or space around the nucleus of an atom in which there is a maximum probability of finding electrons in an atom is called orbital.

2. The energy level that has the lowest energy is known as the ground state of an atom. It is the stable energy level of an atom. But when electrons of the atom gain get excited by the absorption of energy, they are said to be excited. Such excited electrons then jump from lower to higher energy levels. So when an electron moves to a higher energy level, the atom is said to be in an excited state.

3. Mendeleev’s periodic table was the arrangement of various elements in the increasing order of their atomic masses. This periodic table has only 63 elements in it. The elements with similar properties were placed in the same vertical columns of Mendeleev’s periodic table.

4. Mendeleev’s periodic table was constructed according to the increasing order of atomic masses of different elements. In this periodic table, some spaces were left and these were meant for the elements not discovered at that time. But Mendeleev was able to predict the properties of these unknown elements by calculating their atomic masses and he also named such elements temporarily with the use of prefix “eka”. For example, the unknown element with an estimated atomic mass of 44 was named eka-boron by Mendeleev. Later on, this element turned out to be scandium. So Mendeleev’s periodic table was able to predict the properties of unknown elements.

Learn more:

1. Which property do metalloids share with nonmetals? https://brainly.com/question/802690
2. Which properties are characteristic of group 2 elements? https://brainly.com/question/8226316

Answer details:

Grade: High School

Chapter: Periodic classification of elements

Subject: Chemistry

Keywords: atom, electron, subatomic particle, periodic table, atomic masses, unknown elements, excited state, orbital, columns.