PERIODIC TABLE. Chapter Fifteen: Elements and the Periodic Table 15.1 The Periodic Table of the...
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Transcript of PERIODIC TABLE. Chapter Fifteen: Elements and the Periodic Table 15.1 The Periodic Table of the...
PERIODIC TABLE
Chapter Fifteen: Elements and
the Periodic Table15.1 The Periodic Table of the Elements
15.2 Properties of the Elements
Chapter 15.1 Learning Goals
Differentiate physical and chemical properties of elements.
Explain how the periodic table is organized.
Identify metals, semimetals, and nonmetals on the periodic table.
Investigation 15A
Key Question:How is the periodic table organized?
The Periodic Table
15.1 Physical properties
Characteristics that you can see through direct observation are called physical properties.
Physical properties include color, texture, density, brittleness, and state (solid, liquid, or gas).
Melting point, boiling point, and specific heat are also physical properties.
15.1 Physical properties
A physical change does not result in a new substance being formed.
15.1 Chemical propertiesProperties that can only be observed
when one substance changes into a different substance are called chemical properties.
Any change that transforms one substance into a different substance is called a chemical change.
15.1 The Periodic Table
The periodic table organizes the elements according to how they combine with other elements (chemical properties).
The periodic table is organized in order of increasing atomic number.
15.1 The Periodic TableThe periodic table is
further divided into periods and groups.
Each horizontal row is called a period.
Each vertical column is called a group.
15.1 The Periodic TableAll the elements in
Group 1 of the periodic table form similar compounds.
The metals lithium, sodium, and potassium all form compounds with a ratio of 2 atoms of the metal to 1 atom of oxygen.
15.1 Atomic MassThe mass of individual atoms is so small that the numbers are difficult to work with.
To make calculations easier, scientists use the atomic mass unit (amu).
The atomic mass of any element is the average mass (in amu) of an atom of each element.
15.1 Atomic MassAtomic masses differ from mass numbers because most elements in nature contain more than one isotope.
15.1 Atomic Number Remember, the atomic number is the
number of protons all atoms of that element have in their nuclei.
If the atom is neutral, it will have the same number of electrons as protons.
15.1 Groups of the periodic tableThe first group is known as the
alkali metals. The alkali metals are soft and silvery in their pure form and are highly reactive.
This group includes the elements lithium (Li), sodium (Na), and potassium (K).
15.1 Groups of the periodic tableThe group two metals include
beryllium (Be), magnesium (Mg), and calcium (Ca).
They also bond easily with oxygen.
15.1 HalogensThe halogens tend to be toxic gases or liquids in their pure form.
Fluorine (F), chlorine (Cl), and bromine (Br) form salts when the bond with alkali metals.
15.1 Noble GasesThe noble gases, including the elements helium (He), neon (Ne), and argon (Ar).
These elements do not naturally form chemical bonds with other atoms and are almost always found in their pure state.
Chapter Fifteen: Elements and
the Periodic Table15.1 The Periodic Table of the Elements
15.2 Properties of the Elements
Chapter 15.2 Learning Goals
Differentiate the electrical and thermal conductivity of metals and nonmetals.
Define periodicity and discuss examples.
Predict properties of an element based on its position on the periodic table.
Investigation 15B
Key Question:What information can you get from the
periodic table?
Atomic Challenge
15.2 Properties of the elementsMost of the pure elements are
solid at room temperature.
Only 11 naturally occurring elements are a gas.
Only 2 elements (Br and Hg) are liquid at room temperature.
15.2 Periodic properties of elementsPeriodicity means properties
repeat each period (row) of the periodic table.
This pattern is an example of periodicity.
15.2 Thermal and electrical conductivity
Electricity is the movement of electric charge, usually electrons.
Some materials allow electrons to flow easily through them.
We call these materials electrical conductors.
15.2 Thermal and electrical conductivity
Like copper, most metals are good thermal conductors.
That is one reason pots and pans are made of metal.
15.2 Thermal and electrical conductivity
Elements on the far right of the table are called non-metals.
Nonmetals make good insulators.
An insulator is a material which slows down or stops the flow of either heat or electricity.
15.2 Metals and metal alloysAn alloy is a solid
mixture of one or more elements.
Most metals are used as alloys and not in their pure elemental form.
Yellow brass is an alloy of 72% copper, 24% zinc, 3% lead, and 1% tin.
15.2 Metals and metal alloysTitanium combines the
strength and hardness of steel with the light weight of aluminum.
Titanium, a rare and expensive alloy, is used for military aircraft and racing bicycles.
15.2 Carbon and carbon-like elements
Almost all the molecules that make up plants and animals are constructed around carbon.
The chemistry of carbon is so important it has its own name, organic chemistry.
15.2 Carbon and carbon-like elements
Pure carbon is found in nature as either graphite or diamond.
Silicon is the second most abundant element in the Earth’s crust, second only to oxygen.Why are carbon and
silicon important?
15.2 Nitrogen, oxygen and phosphorus
Oxygen and nitrogen are crucial to living animals and plants.
For example, proteins and DNA both contain nitrogen.
Phosphorus is a key ingredient of DNA, the molecule responsible for carrying the genetic code in all living creatures.
15.2 Nitrogen, oxygen and phosphorus
Proteins and DNA both contain oxygen and nitrogen, making these elements crucial to life.
46% of the mass of Earth’s crust is also oxygen bound up in rocks and minerals.
15.2 Nitrogen, oxygen and phosphorus
Phosphorus is a key ingredient of DNA, the molecule responsible for carrying the genetic code in all living creatures.
When phosphorus atoms absorb light, they store energy, then release it in a greenish glow.
Investigation 15C
Key Question:How do electrons fill
up the energy levels?
Electrons and the Periodic Table
Silicon- The Super ElementAlthough silicon can form a
myriad of useful compounds, it’s best known for its impact on the modern world in the form of the microchip, a miniaturized electric circuit that fits into computers, cellular telephones, microwaves, and other
digital appliances.