Defining the Atom

Atomic Structure

Modern Theory: The

Electron Cloud Model

What is the structure of an atom?

atom is made up of 3 subatomic particles

• protons and neutrons- inside the nucleus

• electron-outside the nucleus

• nucleus-small dense center of an atom

• nucleus- the atomic mass is concentrated

​this is Bohr model of atom

that places the electrons by energy levels

Multiple Choice

The negatively charge particle in an atom is called

• electron

• proton

• neutron

Multiple Choice

Atom is the smallest particle of matter. However, there are 3 particles inside of it that are called subatomic particles. True or False?

• True

• False

• I am not sure

Multiple Choice

The small but dense center of an atom is called

• cloud

• center

• nucleus

Multiple Select

Which pair correctly describe the locations of subatomic particles in an atom?

• electron-inside the nucleus

• proton-inside the nucleus

• neutron-inside the nucleus

• electron-outside the nucleus

Each Element = One Atom

• atomic number (whole number) = to number of protons

• mass number (rounded atomic mass) = the number of protons + number of neutrons

• in a neutral atom, the number of protons equals the number of electrons

• all elements in the periodic table are in ground state (neutral)

• therefore, each atom has same number of protons and electrons which is the same as the atomic number

The Periodic Table

• made of different elements arranged in rows and columns

• each element equals to ONE atom

• an element is identified by its chemical symbol

Atomic Mass or Mass Number

• mass number= the # of protons and neutrons in the nuclues of an atom

• What is the mass of an atom(atomic mass) as shown in the picture?

• Count the number of protons and neutrons=7

• How many protons? 3

• The element # 3 in the PTable

An Atom of Oxygen

• each atom in the PTable is in the ground state

• it is neutral, meaning no charge

• # of protons=# of electrons

What is in the box?

• In an atom of oxygen element

• atomic number= 8

• # protoms = 8

• # of electrons = 8

• atomic number= # of protons = # of electrons, because it is neutral

Atomic Number or # of protons determine the identity of an atom(its element name)

​

Multiple Choice

A chlorine atom has how many protons and electrons?

• proton - 17

  electrons - 17

  mass number - 17

• protons - 17

  electrons - 35

  atomic number- 17

• protons- 17

  electrons - 17

  atomic number 17

• protons-35

  electrons-17

  mass number -35

Multiple Select

In a neutral atom, atomic number is equals to the number of

• protons in an atom

• electrons in an atom

• neutrons in an atom

• atomic mass of an atom

Multiple Choice

The mass number of an atom is determined by adding the number of protons and the number of neutrons. Which is the correct information of the structure of the iron atom?

• protons=26

  electrons=26

  neutrons=26

  atomic number=26

  mass number=56

• protons=26

  electrons=26

  neutrons=30

  atomic number=26

  mass number=56

• protons=26

  electrons=26

  neutrons=56

  atomic number=26

  mass number=56

Multiple Choice

An atom has 19 protons. What is its element name?

• potassium (Po)

• potassium (K)

• neon (N)

• fluorine(F)

Multiple Choice

The atomic number of an element is fixed and it is ALWAYS equal to the element's number of protons. True or False?

• true

• false

• sometimes

Multiple Choice

An atom has 20 protons, 20 electrons, and 20 neutrons. What is the name of the atom?

• potassium (K)

• calcium(Ca)

• neon (N)

• sodium (Na)

Multiple Choice

What is the mass of this atom as shown?

• 6

• 8

• 12

• cannot be determined

Multiple Choice

As shown in the element box information, lithium has ____number of neutrons.

• 3

• 4

• 6

• 7