Question

atomic theory part 2- isotopes
quick review on early atomic theory:
an ______ is the smallest particle of an element that retains its identity in a chemical reaction. the existence of atoms as indivisible units of matter had been suggested 2,400 years ago, but these early ideas lacked experimental support and did not explain chemical behavior.
discovering subatomic particles:
john ____ - his atomic model marks the beginning of atomic theory. much of his atomic theory is accepted today, but we now know that atoms are __. they can be broken down into smaller, more fundamental particles, called ____ particles, including electrons, protons, and neutrons.
in 1897, j.j ____ discovered __, or negatively charged subatomic particles. thomson passed electrical current through electrodes in sealed tubes of gas. the electrons became charged, resulting in a glowing beam/cathode ray. __ rays are attracted to __ charged metal plates and are repelled by a negatively charged metal plate. since opposites attract and like charges repel, thomson deduced that cathode rays are beams of negatively charged particles he named ____.
thomson concluded from his research that the mass of the negative charge was very small compared to the magnitude of the charge. thomson’s model can be thought of as a chocolate chip cookie or chocolate chips in ice cream. the “chips” represent the electrons evenly distributed.
image of a green atom with blue dots, labeled with a blank box
discovering the nucleus:
in ____ model of the atom, electrons travel around the nucleus like around the sun. rutherford experimented using __ ____ and alpha particles.
image of a nucleus with electrons, labeled with blank boxes

Explanation:

To solve this fill - in - the - blank about atomic theory, we refer to the basic knowledge of atomic theory:

1. First blank (smallest particle of an element)

An atom is the smallest particle of an element that retains its identity in a chemical reaction. This is a fundamental definition in atomic theory.

2. John Dalton's atomic theory

John Dalton - his atomic model marks the beginning of atomic theory. Dalton's atomic theory was one of the earliest formalized atomic theories, although we now know that atoms are not indivisible.

3. Indivisibility of atoms (old view)

We now know that atoms are not indivisible. Dalton's original theory proposed that atoms were indivisible, but later discoveries of subatomic particles proved this wrong.

4. Subatomic particles

They can be broken down into smaller, more fundamental particles, called subatomic particles, including electrons, protons, and neutrons.

5. J.J. Thomson's discovery

In 1897, J.J Thomson discovered electrons, or negatively charged subatomic particles. Thomson's cathode - ray experiment led to the discovery of electrons.

6. Cathode rays and charge attraction

Cathode rays are attracted to positively charged metal plates and are repelled by a negatively charged metal plate. Since opposite charges attract and like charges repel, Thomson deduced that cathode rays are beams of negatively charged particles he named electrons.

7. Rutherford's model

In Rutherford's model of the atom, electrons travel around the nucleus like planets around the sun. Rutherford experimented using gold foil and alpha particles (this was the famous gold - foil experiment which led to the discovery of the atomic nucleus).

Answer:

s:

1. atom
2. Dalton
3. not indivisible
4. subatomic
5. Thomson; electrons
6. Cathode; positively; electrons
7. Rutherford; gold foil