Chemistry, Atoms and Periodicity

Atoms and the Periodic Table

by Crystal Winner

Atoms

What Are They?

What Are They Made Of?

How Do We Study Them?

What are atoms made of?

Atoms are made of Protons and Neutrons, located in the Nucleus, and Electrons around the outside of the nucleus.

Multiple Select

What particles are atoms made of? (Check ALL that apply:)

• Protons

• Neutrons

• Electrons

• Nucleus

Multiple Select

What particles are in the nucleus?

• Protons

• Neutrons

• Electrons

• Nucleus

Multiple Select

Which particle is outside the nucleus?

• Protons

• Neutrons

• Electrons

• Nucleus

Protons, Neutrons, and Electrons:

• Protons and neutrons have mass.

• Electrons don't have mass.

Multiple Select

Which two particles have mass?

• Protons

• Neutrons

• Electrons

• Nucleus

Particle Charges:

Protons are positively charged.

Neutrons are neutrally charged.

Electrons are negatively charged.

Multiple Choice

Protons are:

• Positive

• Neutral

• Negative

Multiple Choice

Neutrons are:

• Positive

• Neutral

• Negative

Multiple Choice

Electrons are:

• Positive

• Neutral

• Negative

What's an element?

• An atom is the smallest unit of a chemical element.

• That is, an atom has all the properties of that element.

• All atoms of the same element have the same number of protons.

• An elements atomic number tells us how many protons the element has

Elements can be found on the PERIODIC TABLE OF ELEMENTS!

Multiple Choice

What is the smallest piece of matter that still has properties of that matter?

• element

• atom

• proton

Multiple Choice

Matter is anything that takes up space

• True

• False

Multiple Choice

The three main states of matter are:

• Solid and liquid

• Solid, liquid and gas

• Plasma, liquid and solid

​Each ELEMENT has an ATOMIC WEIGHT that is equal to the number of protons plus the number of neutrons (in one atom of the element).

​

​Oxygen has an atomic number of 8 and atomic mass of 15.999. We can determine the number of NEUTRONS in an oxygen atom.

​

​That's right! We can find the # of neutrons in an oxygen atom because we already know the number of protons.

​

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​The number of protons in an atom is equal to the atomic number of the atom.

An atom of oxygen has 8 protons.

​To find the number of neutrons in an oxygen atom:

1. Round the atomic mass to the nearest whole number.                  2. Subtract the atomic number from the rounded atomic mass.

​1. 15.999 rounds to 16.

2. Atomic mass - atomic number = # of neutrons.

​

Answer: 16-8= 8 neutrons

​Find the number of neutrons in an atom of boron.

1. Round the atomic mass to the nearest whole number.

​2.  Subtract the atomic number from 11.

What is your answer?

​

6 is the number of neutrons in a boron atom.

Great job!​

​How many neutrons are in an atom of lithium?

​

​1. Round the atomic mass to the nearest whole number.

​2. Subtract the atomic number from the atomic mass.

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Multiple Choice

What is the atomic number of this element?

• 70

• 79

• 80

• 200

Multiple Choice

What is the chemical (or element) symbol of gold?

• Ag

• Gold

• Au

• AGT

Multiple Choice

How many neutrons are in an atom of gold?

• 118

• 197

• 128

• 79

Model of carbon atom showing the electrons in different energy levels

• (electrons are blue spheres in this model)

• Carbon's electron configuration is 2-4

• 2 electrons are shown in the 1st "shell"

• 4 electrons are shown in the 2nd "shell"

• 2nd shell elecrons have higher energy than those in 1st shell

Maximum # of electrons in energy levels 1-3 (shells 1-3)

• Max of 2 e^- in Level 1

• Max of 8 e^- in Level 2

• Max of 18 e^- in Level 3

electrons in the outermost shell are called valence electrons

These are the most important electrons of an atom.

Carbon has electron configuration 2-4. It has 4 valence electrons.