The Periodic Table

Introduction to the Periodic Table By 1830 fifty-five different elements had been isolated and named. In 1869 Mendeleev arranged elements in order of increasing atomic mass and found that elements with similar properties fell into groups. Moseley improved the periodic table by arranging the elements according to atomic number instead of atomic mass.

Modern Periodic Table Contains seven period or rows of elements whose properties change gradually and eighteen groups or columns, each with a family of elements having similar properties.

Organization of Periodic Table Groups 1 and 2 along with groups 13 to 18 are called the representative elements. Groups 3 to 12 are called the transition elements.

Metal Has luster Conducts heat and electricity Is malleable and ductile

Nonmetals Are usually gases or brittle solids at room temperature

Metalloids Shares properties with metals and nonmetals

Symbols Are abbreviations usually based on the element’s name

Representative Elements Groups 1 and 2 are active metals found in nature combined with other elements Although hydrogen is placed in Group 1, it is not a metal and it shares properties with Groups 1 and 17

Alkali Metals Silvery solids with low densities and low melting points They increase in reactivity from top to bottom of the periodic table

Alkaline Earth Metals Are denser, harder Have higher melting points Are slightly less active than alkali metals in the same period

Groups 13 through 18 May contain metals, nonmetals, or metalloids in solid, liquid, or gas form. The boron family elements in group 13 are all metals except boron, which is a metalloid; these elements are used in a variety of products.

Carbon Group Elements are all metalloids or metals, except carbon itself Carbon is found in all living things and exists in several forms. Silicon and germanium are used in electronics as semiconductors. Tin an lead are used in many products.

Nitrogen Group Contains nitrogen and phosphorus Which are required by living things Which are used in industry

Oxygen Family Contains oxygen and sulfur Which are essential for life Used to manufacture many products

Halogen Group Elements from salts with sodium and with other alkali metals

Noble Gases Rarely combine with other elements They are often used in lighting and inflating balloons.

Transition Elements Groups 3 to 12 are metals Most are combined with other elements in ores The iron triad is composed of iron, cobalt, and nickel They are used in many applications Several transition elements can be used as catalysts, substance that make a reaction occur faster.

Inner Transition Elements Are called lanthanides and actinides The lanthanides are soft metals and were once thought to be rare. All the actinides are radioactive; several are synthetic elements that do not occur naturally. Dental materials are sometimes made of new composites, resins, and porcelains.

What does reactivity mean? 9F Reactivity in chemistry What does reactivity mean? Elements that are reactive readily take part in reactions with other chemicals. But an element might react very quickly with one chemical and hardly at all with another. So is it reactive or not? To compare the reactivity of different elements, we might see how easily they react with oxygen. Some metals corrode in minutes out on the bench. Others take longer to corrode, unless you heat them.

We can list metals in order of how quickly they react with oxygen. 9F The Gold Cup again? We can list metals in order of how quickly they react with oxygen. speed of reaction with oxygen least reactive most reactive This ranking of metals according to reactivity is called the reactivity series.

What if we react different metals with acid? 9F Reaction of metals with acid What if we react different metals with acid? iron – the metal reacts slowly, producing a few bubbles copper – no bubbles, no reaction with acid lead – the metal reacts very slowly, producing very few bubbles magnesium – the metal reacts quickly with the acid, producing lots of bubbles sodium – the metal bursts into flames, a very strong reaction

reactivity series with 9F What about water? We can also rank metals by their reaction with water. Compare with the reactivity series for oxygen and acid. reactivity series with oxygen acid water potassium sodium magnesium zinc iron lead copper gold potassium sodium magnesium zinc iron lead copper gold The reactivity series is very useful. How can we learn it?

Chapter 4 Properties and Changes of Matter Section 1 – Physical and Chemical Properties Section 2 – Physical and Chemical Changes Pages 104 - 129 4/23/2017

Physical Property Characteristic that CAN be observed WITHOUT changing the composition of the substance. Appearance – properties detected by senses State - can be liquid, solid, or gas 4/23/2017

Physical Property cont… Volume, mass, and density – measurements that describe physical properties Melting point & boiling point are physical properties of a substance Behavior – the way some substances behave 4/23/2017

Chemical Property Characteristic that CANNOT be observed without altering the substance Ability to burn Tendency to rust Reaction to other substances such as acids 4/23/2017

Physical Change Form or appearance of matter changes, but composition stays the same Shape can change, but substance does not Example: Dissolving a solid into a liquid Changing states through vaporization, condensation, sublimation, or deposition does not change the composition of matter. 4/23/2017

Chemical Change Results in a change in the substance’s composition Color can change Odor sometimes changes Formation of gas or precipitation of a solid Energy is gained or released during a chemical change Chemical changes are NOT easily reversed. 4/23/2017

Big Difference Chemical changes DO alter the composition of substances Physical changes DO NOT alter the composition of substances Examples: water freezes or evaporates – amount of matter stays the same -> physical change Wood burns – ashes, smoke, and gases still total the same amount of matter -> chemical change. 4/23/2017

Law of Conservation of Mass Particles of matter are not created or destroyed as the result of physical or chemical changes. 4/23/2017