unit i: alchemy

UNIT I: ALCHEMYSECTION II: BASIC BUILDING MATERIALS

COMPOSITION OF MATTER

ALL MATTER IN THE UNIVERSE IS AN ELEMENT OR IS MADE OF

SOME COMBINATION OF ELEMENTS!

ELEMENT

Element- a unique substance that cannot be broken down into simpler substances through chemical processes.

Elements are the building blocks of matter. Elements are found on the periodic table. The first letter of an element’s symbol is

ALWAYS uppercase and if there is a second letter it is ALWAYS lowercase.

EX.

COMPOUNDS

Compounds- a pure substance that is a chemical combination of two or more elements in a fixed ratio.

Compounds are represented by chemical formulas.

Compounds can be broken down into simpler stable substances.

Ex.

CHEMICAL FORMULAS

Chemical Formula- a combination of symbols and subscripts that indicates the number and types of elements in a compound.

Ex. CuSO4

Ex. Li2S

Ex. NaCl

Phases of Matter

Matter can come in different physical forms called phases.

Phase- the physical form a substance is in, such as solid, liquid, or gas.

Phases are influenced by temperature.

Solid (s), liquid (l), gas(g)

Aqueous

Aqueous- a substance that is dissolved in water.

Aqueous (aq)

What is the difference between Nacl(l) and NaCl(aq)?

Chemical Change

Chemical Change- a change in which one or more substances change into entirely new substances with different properties.

Examples:

Chemical Reactions

Chemical reaction- process by which one or more substances change to produce one or more different substances.

Examples:

What are some indicators that chemical reaction has taken

place?

•Precipitate Formation

•Odor

•Release/Absorption of Energy

•Bubbles/Gas Production

Products & Reactants

Reactants-substances that exist prior to a chemical reaction.

Products- substances that are formed as a result of a chemical reaction.

carbon + oxygen carbon dioxide

C (s) + O2 (g) CO2(g)

reactants product

Carbon reacts with oxygen to form/to yield carbon dioxide.

Basic Laws of Matter

Law of Conservation of Mass- mass is neither created or destroyed during ordinary chemical reactions or physical changes.

A + B → AB 1mu 3mu 4mu

Antoine Lavoisier

History of the Periodic Table

In 1869, Dmitri Mendeleyev’s published the first periodic table.

Mendeleev arranged the elements horizontally by increasing atomic mass and placed elements in groups (vertically) based on similar properties.

History of the Period Table

Mendeleyev’s Periodic Table

History of the Periodic Table

Mendeleyev’s Periodic Table

Mendeleev’s procedure left many holes throughout the periodic table.

Mendeleyev was able to predict the properties of elements that would eventually fill those holes even though they were not discovered yet.

Ex. Ekasilicon- Germanium

Average Atomic Mass

Average Atomic Mass- the mass of one atom of a given element measure in atomic mass units (amu).

Located beneath the elements symbol on the periodic table.

Atomic mass units are extremely small units.

History of the Periodic Table

In 1913, Henry Moseley developed the Modern Periodic Table. He arranged periodic table in rows by increasing atomic number and in columns by similar properties.

History of the Periodic Table

Moseley’s Accomplishments: Discovered that the positive charge of the

nucleus increases from one element to the next.

Led to the modern definition of atomic number.

Moseley’s periodic table explained some of the contradictions that Mendeleev experienced within his model.

History of the Periodic TableEarly 1900’s

Moseley’s Periodic Table

Atomic Number

Atomic Number- Number of protons in an atom.

Located above the elements symbol on the periodic table.

Periodic Law

Periodic Law- states that the chemical & physical properties of the elements are periodic function of their atomic numbers.

Group/Family- vertical columns of elements on the periodic table with similar properties.

Periods- horizontal rows of elements on the periodic table arranged by increasing atomic number.

Metals, Nonmetals, & Metalloids

Metals Make up most of the periodic table. Ductile- can be drawn into wire Malleable- can be hammered into thin

sheets. Lustrous- shiny Good Conductors of heat & electricity Located to the left of the step ladder on the

periodic table.

Metals, Nonmetals, & Metalloids

Nonmetals Brittle-break when hammered. Poor conductors of heat & electricity. Lack luster Located to the right of the step ladder on

the periodic table.

Metals, Nonmetals, & Metalloids

Metalloids Semimetals. Properties of both metals & nonmetals. Located along the step ladder on the

periodic table. Examples: B, Ge, Sb, Te, At, Si, As, Po

Metals, Nonmetals, & Metalloids

Alkali Metals- Group 1A

Most reactive group of metals.

Usually found in combined form as a salt due to their high reactivity.

Combine vigorously with nonmetals especially groups 6A & 7A .

React readily with water. Soft and silvery appearance.

Alkaline Earth Metals- Group 2A

Found in the earth’s crust but not in the elemental form due to their high reactivity. They are usually found in rock structures.

2nd most reactive group of metals. More dense than group 1. Shiny silvery-white color.

Transition Metals- Groups 1B-8B

Typical metallic properties.

Good conductors. Lustrous. Produce colored

ions.

Main Group Elements Groups 1A-8A

Properties of elements vary greatly. Contains all of the nonmetals & metalloids

as well as some metals.

Halogens -Group 7A

Most reactive groups of non-metals. React vigorously with metals (especially

groups 1A & 2A) to produce salts. Fluorine is a poisonous pale yellow gas,

chlorine is a poisonous pale green gas, bromine is a toxic and caustic brown volatile liquid, and iodine is a shiny black solid which easily sublimes to form a violet vapor on heating.

Found in nature in the combined state.

Noble Gases- Group 8A

Least reactive of all elements. Often called inert gases. All are gases. The noble gases are all found in

minute quantities in the atmosphere, and are isolated by fractional distillation of liquid air.

Inner Transition Metals- Periods 6 & 7

Lanthanides (Period 6)- Rare Earth Metals

Shiny reactive metals

Actinides (Period 7) Unstable & radioactive metals. Most are laboratory made.

Reactivity of Metals Trend

Period Trend- Metals increase in activity from right to left on the periodic table.

The alkali metals are the most reactive group of metals.

Group Trend- Metals increase in reactivity from top to bottom with a group.

Ra is the most reactive alkaline earth metal.

Reactivity of Nonmetals Trend

Period Trend- Nonmetals increase in activity from left to right on the periodic table with the exception of the noble gases.

The halogens are the most reactive group of nonmetals.

Group Trend- Nonmetals increase in reactivity from bottom to top with a group.

F is the most reactive halogen.

Reactivity Trends

What is the most reactive metal on the periodic table? Explain.

Circle the most reactive nonmetal in each row:

1. Te Po S2. Br I Cl