dmitri mendeleev

Dmitri MendeleevProfessor Dmitri Mendeleev published the first Periodic Table of the Atomic Elements in 1869 based on properties

which appeared with some regularity as he laid out the elements from lightest to heaviest. When Mendeleev proposed his periodic table, he noted gaps in the table, and predicted that as-of-yet unknown elements existed with properties appropriate to fill those gap.

He wrote names and properties of elements on cards. Then he arranged the cards by properties, such as density, appearance, and melting point.

Mendeleev then ordered the elements by increasing atomic mass, a pattern began to appear.

– When arranged by increasing atomic mass, those elements with similar properties occurred in repeating patterns.

The Periodic Table

The periodic table of elements is a chart that provides valuable information about all of Earth’s known elements.

There are eighteen columns on the periodic table. These columns are called families or groups. Elements in the same family or group have similar characteristics.

Families of the Periodic TableThere are 8 families on the periodic table that have specific names:

Family 1 – Alkali Metals

Family 2 – Alkaline Earth Metals

Family 13 – Boron Family

Family 14 – Carbon Family

Family 15 – Nitrogen Family

Family 16 – Oxygen Family

Family 17 – Halogens

Family 18 – Noble Gases (this family contains only gases)

Families 13-16 get their name from the first element in the family.

The other ten families (3-12) are called the transition metals.

The Elements: Elements 1 (hydrogen) through 92 (Uranium) are the Natural Elements.

Building blocks of matter on earth.

43 (Technetium) and 84 (Polonium) are not found naturally on earth. Elements 43, 84, and all elements beyond 92 are Artificial or Synthetic Elements.

Produced by nuclear reactions in the laboratory.

The Periodic Table

Vocabulary

Element – A substance that cannot be broken down into smaller substances.

Atom – The smallest unit of an element.Family – a column on the periodic table.Group – another name for a family on the

periodic table.

Periodic Table

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VocabularyFamily – a column on the periodic table.

Group – another name for a family on the periodic table.

Element – A substance that cannot be broken down into smaller substances.

Atom – The smallest unit of an element. Atoms are made up of subatomic particles.

Protons Neutrons Electrons

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Atomic Number – The number of protons. Also the number of electrons in an uncharged atom.

Atomic Mass – The average total mass of protons, neutrons, & electrons.

Symbol

Subatomic Particles

Protons – Have a positive (+) charge and are located in the nucleus or center area of the atom.

Neutrons – Have no charge/ or are neutral and are located in the nucleus of the atom.

Electrons – Have a negative (-) charge and are located outside of the nucleus.Electrons are very small and move very fast making

their location difficult to pin point. The general area where they are located is called an electron cloud or orbital.

The Big Question

How are atoms of one element different from the atoms of another element?

The atoms of each element has a different number of protons.

This is distinguished by the atomic number – the number of protons in the nucleus of the atom/element.

CompoundsCompound - When two or more elements are held together by

chemical force or bond. Ionic Bonds – A bond where electrons are transferred from one atom to

another. Covalent Bonds – A bond where atoms share electrons.

Bonding – The combining of atoms.

Molecule – 1. The smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms. 2. A group of like or different atoms held together by chemical forces.

Ionic & Covalent Bonds

Atomic Charge & Ions

When an atom gains or looses an electron, the atom is no longer neutral and therefore has a charge.

An atom with a charge is an Ion.

The number of protons never change in an atom.

Water Molecule

Compound of WaterH2O

Hydrogen (H) – Colorless, odorless gas. Very light and highly explosive when it meets air.

Oxygen (O) – A clear, colorless gas. Very flammable.

Water (H2O) – A nonflammable liquid.

The number of atoms in each compound are fixed in ratio.

Water cannot be separated into H & O by physical methods – only a chemical reaction can separate a molecule into it's component elements.

Metals

Non-Metals & Metalloids

States of Matter

Water can be found in solid, liquid and gas forms. How does this happen?

Solid, liquid and gas are the names of different physical forms or phases of matter. Also called States of Matter.

- Solids – Made of closely-packed atoms or molecules and maintain a rigid form without a container.

– Incompressible – Cannot be 'squeezed' down to a smaller size.

States of Matter

- Solids

- Liquids – Made of closely associated atoms or molecules and will flow to conform to the shape of the container.

– Liquids are mostly incompressible.- Gases – Made of mostly unassociated atoms or molecules and

will expand to fill a container.

– Gases are compressible, their volume can be reduced by applying force.

SolidsSolids are formed when attractive forces between

atoms are greater that the energy causing them to move apart. The atoms are locked in position near each other.

Crystalline Solid – A solid where atoms are in a fixed, structured position.

– Examples: Salt, diamond, quartz, ice.

Amorphous Solid – A solid with no structure.– Examples: Wax, many foods, like cotton candy.

Solids

In the solid phase, atoms cannot move past one another. Even in this state, atoms still have energy and move. Atoms in the solid phase vibrate.

- As the temperature of a solid increases, the amount of vibration increases. The solid will keep its shape until the amount of energy added is greater than the attractive forces between the atoms. Now the atoms start to move more freely... forming a liquid.

The temperature at which a solid become a liquid is called it's?

Melting Point

LiquidsIn liquids, atoms can move past on another and

bump into each other. This is why liquids can “flow” to take the shape of their container. Atoms in a liquid still stay relatively close together.

- As the temperature of a liquid and motion of the atoms is increases, the amount of movement of individual atoms increases. They bump into each other with increasing thermal energy. Eventually some particles have enough energy to “escape.” These atoms have entered the gas phase.

The temperature at which a liquid become a gas is called it's?

Boiling Point

GasesAtoms and molecules in the gas phase have little interaction with

each other. Gases have low density, meaning there are few particles occupying a given space.

- Increasing the temperature of a gas increases the movement of the gas particles. When in a fixed container the increased movement of the gas will cause them to hit the walls of the container with greater frequency and force. This creates increased pressure.

Thermal Energy

Physical & Chemical Changes

Chemical Change – When one substance is changed into something else. Irreversible.

Physical Change – A change in a substance where the substance stays the SAME. Reversible.

Mixtures and Compounds

Homogeneous & Heterogeneous Mixtures

Examples of Mixtures

Chemical Changes

Possible Signs of a Chemical Change:

- Heat is produced that was not there before.

- Light is produced that was not there before.

- Fumes or smoke are produced.

- The substance fizz (means a gas phase material is being produced.)

- Solid substances appear. Percipitate.

- Substances change color.

- Substances smell different.

Chemical Reactions

Factors that affect a chemical reaction:- Increasing temperature- Increasing pressure- Increasing concentration- Increasing particle movement (thermal energy)- Increasing surface area.