ATOM

Which of the following statements is NOT TRUE about Democritus atomic theory?

• solid

• indestructible

• collides with each other

• smaller particles are charged.

Which statement is true according to Dalton's theory?

• Atoms of different elements can join to form larger atoms.

• Atoms can be subdivided into smaller particles.

• Atoms of the same element differ in electric charge.

• Atoms of the same element are exactly alike.

An atom has 25 protons and 30 neutrons. How many electrons are needed to make the atom neutral?

• 0

• 25

• 30

• 35

In 1904 JJ Thompson discovered that atoms actually contained particles called electrons. Which of these best describes an electron?

• Much much smaller than the other particles, positively-charged

• Much much smaller than the other particles, negatively-charged

• Make up most of the mass of the atom, negatively-charged

• Contain most of the mass of the atom, no charge

When 24.3 g magnesium reacts completely with 16.0 g oxygen, exactly 40.3 g magnesium oxide is formed. Which of the following law is illustrated by this observation?

• Law of Definite Proportion

• Law of Conservation of Mass

• Law of Multiple proportion

How did each model of the atom helped to develop the atomic theory?

• Each model provided opinions that were added.

• Each model showed different properties of the same structure.

• Each model showed new particles that had been discovered.

• Each model contributed the other to modify and update the theory.

Group Name and Number for Magnesium

• Alkaline Earth Metals 2 or 2A

• Noble Gases 18 or 8A

• Halogens 17 or 7A

• Alkali Metals 1 or 1A