Unit 2 Atoms, Elements, and the Periodic Table
Jan 14, 2016
Unit 2
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
Fun Scientist Spotlight
Leonardo di ser Piero da Vinci
Facts about da Vinci
Born April 15, 1452 to unmarried parents, thus received no last name
Never attended school
He was a vegetarian
Was left handed, and wrote in mirrored script
Never married Pink was his
favorite color…it made his complexion look fresh
Loved animals…would buy caged birds just to set them free
Left over half of his works incomplete
He personally destroyed many of his drawings and paintings
Painted the Mona Lisa, and The Last Supper along with many others
Fascinated with human anatomy – dissected over 300 bodies
Sketched The Vitruvian Man
An Inventor Parachute, hang
glider, helicopter, airplane, barreled organ, machine gun, armored tank, motor car, humanoid robot, 220 meter bridge – still in use today
Mechanical Engineer
Botanist Map Maker Astronomer Mathematician
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 electrons
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?