Chapter 3

Atoms, Elements, and the Periodic Table

Important Vocabulary

Matter Atom Law of Conservation of

Matter Electron Nucleus Proton Neutron Element

Atomic Number Isotope Mass Number Atomic Mass Metal Non-Metal Metalloid Substance Compound Mixture

Launch Lab

Get into your Science Teams Look at the materials provided as I

give you directions Question: Will you see all three

states of matter in this lab activity Write your hypothesis Perform the Experiment

Launch Lab Discussion

What happened to the paper towel? What caused this result? Conclusion:

Water was the liquid state of matter The paper towel was a solid The air in the cup was the gas Air is matter because it occupies space

What is matter?

Look at figure 1 on page 72. What in these pictures is matter?

Matter is anything that has mass and takes up space

Name some things that are not made up of matter.

Atoms

A small particle that makes up most matter

In your science journal, draw what you think and atom looks like

At one time was believed to be a solid unit Now broken into even smaller particles

Neutron, electron, and proton

Democritus

Greek philosopher, lived from 460BC to 370 BC

Claimed that each type of matter was made up of specific atoms For example: solid

water (ice) is made of different atoms than liquid water

His ideas were ignored until the early 1800s

Lavoisier’s Contribution

French chemist, lived 2000 years after Democritus

Law of Conservation of Matter- Matter is neither created nor destroyed. It simply changes form

When you burn wood, what happens to the log?

John Dalton

Stated that matter is made up of atoms that are too small to be seen

Claimed that each element was made up of specific atoms that were unique to that element

His findings are known as the atomic theory of matter

JJ Thomson

Observed that electricity flowed from negative to positive components of a sealed tube and could be bent by a magnet

He knew that opposites attract and the beam was traveling towards a positive charge, so therefore the beam must be made of negatively charged particles Electrons- subatomic particles with a negative

charge

So what keeps us from being electrocuted? You don’t get a shock when you

touch everything, so what must also be present in the atom?

A positively charged particle The proton

Ernest Rutherford

In 1910, his team shot gold foil with alpha particles Positively charged particles

Since all of the alpha particles did not pass through the foil, he predicted that most of the atom was made up of empty space

Rutherford’s results provided him with information to name the nucleus Nucleus- Positively charged central part of the

atom Contains protons

James Chadwick

Assistant to Rutherford Discovered the neutron- neutral

particle in the nucleus Found this data when he noticed

that the gold atoms in the foil had released some mass with no charge That unknown mass is what Chadwick

called the neutron

Modern Atomic Model

Look at Figure 8 on pg. 78 This model is the accepted atomic

model (Bohr’s Model) Notice the negatively charged

electron cloud and the positively charged nucleus

New Research

Modern science has advanced atomic research Protons and electrons have whole charges +1

or -1 The particles in the nucleus are now broken

down into even smaller particles called quarks These particles are identified by their spin pattern

and have a fractional charge Up, down, strange, charmed, top, and bottom

The Simplest Matter

Element- matter made up of only one kind of atom

At least 115 elements are known and 90 of them occur naturally on Earth

Non-natural elements are known as synthetic elements Formed from nuclear reactions in

machines known as particle accelerators

Organizing the Elements

Dmitri Mendeleev organized the first periodic table in order of each element’s mass

His table only included 60 known elements

The modern Periodic Table is organized by atomic number

The Periodic Table

Structure and Organization of

Important Vocabulary Matter Atom Law of Conservation

of Matter Electron Nucleus Proton Neutron Element

Atomic Number Isotope Mass Number Atomic Mass Metal Non-Metal Metalloid Substance Compound Mixture

What is an Atom?

An atom is the simplest form of matter It is made of three major particles

The Proton – Positive Charge, In the Nucleus

The Electron – Negative Charge, In the Shells and Orbitals

The Neutron - No Charge, In the Nucleus

Let’s Draw an Atom

+ + +

- -

-

Notice a few things about our atom… How many protons does it have? How many neutrons does it have? How many electrons does it have? What is the object in the center? How many rings does it have? How many electrons are on the

outside ring?

What do protons mean?

The number of protons is also the atomic number of the atom/element Example: Hydrogen, atomic symbol H, has 1

proton since it is element #1 How many protons does each of these have?

Beryllium, Oxygen, Nitrogen, Xenon, Carbon Name the element with the number of

protons shown. 14, 27, 5, 30

What do Neutrons mean?

If you add the number of neutrons and protons, you get the atomic mass This is the decimal number underneath

the atomic symbol Example:

Magnesium is element #12 How many protons? Its atomic mass is 24.3050, which rounds to 24. How many neutrons does Magnesium have?

What do electrons mean?

Electrons are the negatively charged particles located in the rings around the nucleus

There are exactly the same number of protons as there are neutrons

How many electrons: Sodium – Atomic Number 11 Silicon – Atomic Number 14 Arsenic – Atomic Number 33

What is the thing in the center? That is the nucleus

Review: What two particles are in the nucleus? What overall charge does the nucleus have?

What do the rings mean?

The number of rings tells you on which row the element is located Hydrogen has how many rings? How many rings does Helium have? What about Carbon? What about Iodine?

What do the outer electrons mean? The outer ring electrons are called valence

electrons These tell you to which column or family

the element belongs Special Note: This only applies to families

1,2 and 13-18 How many valence electrons does Hydrogen

have? Neon? Aluminum? Now for Rules on Rings…

Ring Rules

The inner ring, #1, can only have 2 electrons The second ring can have up to 8 electrons The third ring can have up to 18 electrons The fourth ring can have up to 32 electrons All rings up to ring #7, the last ring, can

have up to 32 electrons KEY VOCAB: Energy Level – the rings

containing electrons are actually called energy levels

1

2 3 4 5 6 7

8

Transition Metals DO NOT Follow Rules

1

2

3

4

5

6

7

Naming the Elemental Families

Transition Metals

Organization on the Periodic Table Rows are called families

Have the same number of energy levels Columns are called groups

Have the same number of valence electrons and bond similarly

Isotopes

What do you know about isotopes? Atoms with the same number of protons,

but different numbers of neutrons Isotopes determined by mass number (the

sum of protons and neutrons in the nucleus) Mass number on the periodic table is the

average mass of the element

Hydrogen Isotopes

Hydrogen has three isotopes Protium

1 proton, 0 neutrons Most abundant

Deuterium 1 proton, 1 neutron

radioactive

Tritium 1 proton, 2 neutrons

radioactive

Element categories

Metals- shiny, metallic luster, good conductors of electricity and heat All metals are solid at room temperature except

mercury (liquid) Non-metals- usually dull in appearance, brittle (can

change shape)– be familiar with figure 17 Usually poor conductors of electricity Many are gasses at room temp

Metalloids- characteristics of metals and nonmetals, found in a stairstep pattern between metals and non-metals All are solid at room temp

Metalloid Stairstep

Compounds and Mixtures

Substance- mixture with the same chemical properties throughout

Compound- substance whose smallest unit is made up of atoms of two or more elements Have properties different than the

elements that make up the compound

Compound Example

What are some properties of hydrogen? What are some properties of oxygen? What are some properties of the

compound made up of 2 hydrogen atoms and 1 oxygen atom?

What about 2 hydrogen and 2 oxygen?

Compounds

Have formulas Naming the formulas

Prefixes: mono-, di-, tri-, quad-, pent- hex-, hepto-, octo-, nono- deca-

Suffixes: -ine, -ane, -ite, -ate, -ous Let’s practice a few naming problems

Name these:

Sodium (Na) + Chlorine (Cl) = NaCl Hydrogen (H) + Oxygen (O) = H2O Hydrogen (H) + Chlorine (Cl) = HCl Carbon (C) + Oxygen (O) = CO2

8 Hydrogen (H) + 3 Carbon (C) = H8C3 Hydrocarbons have special naming techniques- we

will discuss these techniques in Chapter 9

Mixtures

When two substances (elements or compounds) do not combine to make a new substance when mixed

What happens when you combine oil and water?

Observe the bottle I have prepared.

Two kinds of Mixtures

Homogeneous- the same throughout Examples: Teas, Soda, Fruit flavored soft

drinks Heterogeneous- larger components

that are visibly different from one another Examples: Salads, cookies, mixed nuts

A Quick Review

Describe and name the parts of an atom

Name 5 things that are matter and five things that are not matter

What is the difference between atomic mass and atomic number?

Name and describe the Isotopes of Hydrogen

A quick Review

What is an isotope and what makes them possible?

Solve: An atom of Phosphorous has 15 protons and 15 neutrons, what is the mass number?

Solve: The element Tungsten has a mass number of 184, how many neutrons does Tungsten have?

A Quick Review

What is the difference between homogeneous and heterogeneous mixtures?

What three types of elements are there and give properties of those elements?