Unit 3 Lesson 1

Question 1

Atom

Answer 1

The smallest particle into which an element can be divided and still be the same element

The basic unit of matter

Question 2

Electrons

Answer 2

Negatively charged particles within an atom. Found outside the nucleus

Question 3

Nucleus

Answer 3

The small, dense center of the atom. It has a positive charge and is surrounded by electrons

Question 4

Protons

Answer 4

Positively charged particles inside the nucleus

Question 5

Neutrons

Answer 5

Particles in the nucleus that don’t have a positive or a negative charge

Question 6

Electron Cloud

Answer 6

The area around the nucleus that electrons move in

Question 7

Parts of the Atom

Answer 7

Proton - positively charged. The relative charge is written as 1+. Slightly less massive than neutrons

Neutron - no electric charge . A little more massive than protons

Electrons - negatively charged. The smallest particles. (have very little mass). The charge is written as 1-

Question 8

Atomic Number

Answer 8

The number of protons in the nucleus of an atom

All atoms of a certain element have the same number of protons

Question 9

Isotopes

Answer 9

Atoms of the same element that have different numbers of neutrons

Question 10

Mass Number

Answer 10

The total number of protons and neutrons in an atom’s nucleus

Question 11

Scientists

Answer 11

Democritus - proposed that matter is made of atoms

John Dalton - suggested that atoms were solid spheres

Ernest Rutherford - discovered the nucleus

Niels Bohr - introduced the idea of electrons orbiting the nucleus

Question 12

Current atomic theory

Answer 12

Atoms are the basic unit of matter. The atoms of a particular element are the same
Electrons move within an area around the nucleus called the electron cloud