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•Organizing the Elements•Metals
•Nonmetals and Metalloids
Matter is composed of Elements…
There are over 100 different elements with a wide variety of properties.
Some form compounds easily, while others do not.
Mendeleev, the dirty detective…
-Observed the mass, reactivity, and general properties of various elements.
- Noticed patterns among the elements and began sorting them in order of increasing atomic mass.
Chlorine
Bromine
Group 17 Nonmetals…
1. All poisonous as gases
2. All react easily to form salts
Lithium
Sodium
Potassium
Group one metals…
1. All are soft gray metals
2. All very reactive
3. All form salts
In 1869, Mendeleev Published the first Periodic Table based on his findings…leaving blank spaces for elements that haven’t been discovered yet!!!
Inside an atomAn atom is the smallest unit of matter that still retains the properties of a particular element.
Atoms and the P.T.
An “atomic mass unit” or AMU is equivalent to the mass of one proton/neutron.
Since electrons have virtually no mass, the “atomic mass” of an element refers to the number of protons and neutrons in found in its nucleus….
Atoms and the P.T. (cont…)
However…atoms of various elements sometimes have different number of neutrons in their nuclei, so in actuality, atomic mass refers to the average mass of one atom of a particular element.
Atoms and the P.T. (cont…)
For example….99% of all the helium atoms in the world have 2 neutrons. However, 3 out of every 1,000 have 3 neutrons instead of 2. Therefore, on the P.T. helium has an atomic mass of 4.003 AMU’s
Atoms and the P.T. (cont…)
“Atomic Number” refers to the number of protons in an atom’s nucleus
Elements are arranged on the P.T. according to atomic number. ***Atomic number
(# of protons) is a unique property***
Organization of the Periodic Table
An element’s properties can be predicted by its location on the Periodic Table…
The P.T. is divided into 18 individually numbered columns called “families.”
(also known as a “group”)
Organization of the Periodic Table (Cont…)
Every element in the same family has similar properties.
Group 1 metals all react violently with water…
Group 18 non-metals are inert, in other words, they don’t react with anything.
Organization of the Periodic Table (Cont…)
A horizontal row across the P.T. is called a “period.”The elements in a row do not have similar properties…As you move across a period, the elements gradually change properties.
Why the table works…
An element’s ability to bond with an atom of another element its called its “bonding power”
Bonding power, is determined by the outermost electrons surrounding an atom…the “valence electrons.”
Metals…What is a Metal?
Metals are found to the left of the zigzag line on the P.T.
They are classified based on their physical properties: hardness, shininess, malleability, and ductility.
Metals: Physical Properties
Malleability- The ability of a metal to be pounded into shapes
A “ductile” material is one that can be pulled out or “drawn” into a long wire.
Metals: the Chemical Properties
The ease and speed in which an element reacts with other elements is called its “reactivity.”
Metals show a wide range of chemical properties, or reactivity.
For example……
Metals: the chemical properties
Iron will react with oxygen in the air to form iron oxide (rust).
Gold and chromium are unreactive.
Metals: the Physical properties
Shininess•Hardness
•Magnetism •Conductivity
Alloys
An “alloy” is a mixture of metals…alloys combine the beneficial attributes of 2 or more metals from the P.T.
For example….
Alloys (cont…)
Iron rusts easily, but when mixed with vanadium and chromium, it forms stainless steel.
Alloys (cont…)
Copper is soft and malleable, but when mixed with tin, it forms bronze…an attractive and durable alloy.
Metal families: the alkali metals
The group 1 metals are also known as the alkali metals.They are so reactive that they are never found uncombined in nature.They are so soft, you could easily cut them with a knife.
Metal families: the alkaline earth metals
Group 2 metals are also very reactive, but not as much as group 1.They are also not found uncombined in nature.They are white, hard, and good conductors of electricity.
Metal families: the transition metals
These metals form a bridge between the reactive metals on the left side of the P.T., and the less reactive metals and other elements on the right side of the P.T.
They become less and less reactive as you move from left to right on the P.T.
Lanthanides and Actinides
Also known as the “rare earth elements,” Lanthanides and Actinides are rare, soft, malleable metals.
Some actinides are highly radioactive (they have unstable nuclei)
Metalloids
On the border between the metals and the non-metals are the “metalloids.”Metalloids have some properties of metals and some properties of non-metals. As “semiconductors” they’re varying ability to conduct electricity makes them useful in industry
Metalloids
Metalloids
The Nonmetals…
All 17 nonmetals are extremely important to living things.
They are all found (except for hydrogen) to the right of the zigzag line on the P.T.
Most are gases, some are crumbly solids, and Bromine is the only liquid.
The Nonmetals…
Chemical properties of nonmetals
Most all nonmetals react easily to form compounds.
When metals and nonmetals combine, metal elements transfer their valence electrons to the nonmetal.
Chemical properties of nonmetals (cont…)
When nonmetals combine to form compounds with other nonmetals, valence electrons are shared between two atoms.
Diatomic chlorine (Cl2)
Chemical properties of nonmetals (cont…)
A molecule that contains only 2 atoms (usually the same element) is called a “diatomic molecule.”
Families of nonmetals: The carbon family
In this family, carbon is the only nonmetal. All living things contain compounds composed of long chains of carbon atoms.
Families of nonmetals: The Oxygen Family
- The Oxygen we breathe is essential in allowing our bodies to function.
-Oxygen and sulfur form compounds very easily.
Families of nonmetals: The Halogens
Group 17 elements are known as the halogens, and are very reactive.
They are dangerous to humans, but form compounds that are very useful.
Families of nonmetals: The Noble Gases
These gases have a full valence shell (8 electrons), and do not react at all with any other elements.
They are found in small amounts in the atmosphere and glow brightly when electricity passes through them.
Group 18 non-metals are inert, in other words, they don’t react with anything.
Hydrogen: the simplest element
One hydrogen atom contains only one proton and one electron.90% of the atoms in the universe are hydrogen.When an electric current passes through water, chemical bonds are broken and diatomic hydrogen gas (H2) is formed.
“That’s All Folks!”
More to come…
