STRUCTURES & BONDINGTitle 19/04/23

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MATTERMATTER

MATTER is anything MATTER is anything that has mass and that has mass and

takes up space.takes up space.

STRUCTURES & BONDINGATOMS 19/04/23

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“WHAT IS MATTER MADE FROM?”

A question which has been asked from the ancient Greeks up to 19th century.

In 530 B.C., Democritus, a Greek philosopher proposed that any matter could be halved continuously until small indivisible units could be reached.

STRUCTURES & BONDINGATOMS 19/04/23

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“WHAT IS MATTER MADE FROM?”

The ideas proposed by the Greeks were generally unaccepted until in 1808, John Dalton (a teacher!) proposed the modern ATOMIC THEORY.

From his experiments he found that only elements combined to form compounds. He soon realised that elements were made up of tiny indivisible spheres he called ATOMS.

ATOM

STRUCTURES & BONDINGATOMS 19/04/23

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Atoms are the building blocks of matter.

They are so small you cannot see them with normal microscopes

Try cutting a strip of paper as small as you can….

An atom would be another 40 cuts from the smallest possible cut…at least!

ATOM

STRUCTURES & BONDINGELEMENTS 19/04/23

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“WHAT IS AN ELEMENT?”

An element is a substance which is only made up of one type of atom.

Example, Carbon is made up of Carbon atoms.

STRUCTURES & BONDINGSTRUCTURE OF THE ATOM 19/04/23

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All matter is made up of atoms, but….

“WHAT ARE ATOMS MADE FROM?”

Atoms are made up of even smaller subatomic particles called:

ELECTRONS

PROTONS

NEUTRONS

-+

++++

+

+++ +

+++

+Nucleus

STRUCTURES & BONDINGSTRUCTURE OF THE ATOM 19/04/23

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In the middle of an atom, the NUCLEUS can be found.In nucleus, PROTONS and NEUTRONS can be found.

Orbiting the nucleus in

SHELLS, ELECTRONS

can be found.

-

-

- -

-

-

-

-

-

-NOT TO SCALE!.

- -

-

-

-

-

-

-

ATOM

STRUCTURES & BONDINGSTRUCTURE OF THE ATOM 19/04/23

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The gap between electron shells and nucleus is very large on a subatomic scale.

If an atom was the size of a stadium……the nucleus would be the size of a pea on the centre spot!!

STRUCTURES & BONDINGTHE SUBATOMIC PARTICLES 19/04/23

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Each subatomic particle has a MASS and a CHARGE.ATOMIC PARTICLE RELATIVE MASS RELATIVE CHARGE

PROTON 1 Unit +1NEUTRON 1 Unit 0ELECTRON 1/1840 (NOTHING!) -1-

+

(Masses and Charges are RELATIVE which means in comparison to each other e.g. 1840 electrons will weigh the same as 1 proton.)

STRUCTURES & BONDINGCHARGES 19/04/23

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In an atom, the number of electrons is equal to the number of protons.

This means that since there is a balance between the number of positive and negative subatomic particles there is NO OVERALL CHARGE. An atom must be electrically neutral

++

--

-

--

+++

BORON ATOM

No Charge5 Electrons

(5 Negatives)

5 Protons (5

Positives)

The structure of the atom

MASS NUMBER (Atomic Mass) = number of protons + number of

neutrons

Atomic SYMBOL

Atomic NUMBER = number of protons = number of electrons

STRUCTURES & BONDINGCOMPOUNDS 19/04/23

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“WHAT IS A COMPOUND?”

A compound is a substance which is only made up of two or more elements chemically bonded.

Example, Sodium Chloride is made up of Sodium and Chlorine Atoms.

Bohr-Rutherford Diagram

• 1. Calculate the number of protons and neutrons.• 2. Write the number of p+ and n0 in the nucleus

with a circle around them.• 3. Draw the number of shells (circles) the atom

has – the period number tells you the number of shells.

• 4. Calculate the number of electrons the atom (same as the number of protons) or ion) has.

• 5. Place in the electrons into the shells. Shell1 – 2 e-, Shell 2 onwards gets 8.

Periodic Table

The periodic table is an arrangement of the elements according to:

• The number of protons, neutrons, and electrons

• Physical Properties - The way they look• Chemical Properties - The way they act

• 80% of the elements in the periodic table are metals

• A smaller group consists of non-metals

• Separating the two are a set of elements called metalloids.

Periodic Table

The Periodic Table

Shows the mass number and atomic number

Gives the symbol of the element

mass number

23 Na

atomic number 11

Groups of Elements

Vertical (up and down) columns on the

periodic table

Indicates the number of electrons on the

outer most shell called valence electrons.

Periods on the Periodic Table

The different rows of elements in the periodic table

are called periods.

Numbered 1-7

The period number of an element indicates the

number of orbitals or shells the element

has.

Periods on the Periodic Table

1

2

3

4

5

6

Using The Periodic Table

• In your notes, use your periodic tables to determine the following for the elements at the bottom.– The number of protons– The number of neutrons– The number of shells– The number of electrons on the outer most shell

(valence electrons)– Draw the atoms for each

Calcium (Ca), Magnesium (Mg), Chlorine (Cl)

• Isotopes: atoms of the same element that have a different number of neutrons.

• Atomic mass is the average mass of all isotopes of a particular element

• Family is a group of elements with similar properties arranged together in columns.

• Alloys are a mixture of two or more metals.

Important Terms

The Periodic Table

H He

Li Be B C N O F Ne

NaMg

Al Si P S Cl Ar

K Ca Fe Ni Cu Zn Br Kr

Ag I Xe

Pt AuHg

Alkali metals

Noble gases

HalogensThese elements

are metals

This line divides metals from non-metals These elements

are non-metals

• Most are solid at room temperature

• Most have a shiny appearance (lustrous)

• Their shape can be changed (malleable)

• Can be stretched and drawn into thin wires (ductile)

• Most conduct electricity and heat well

• Usually have high densities (ie. Sink in water)

Properties of Metals

• Poor conductors of heat and electricity or are insulators (don’t conduct at all).

• Low melting and boiling points (usually liquids or gases at room temperature).

• Brittle - if a solid.

• Do not possess metallic luster (so dull)

Properties of Non-Metals

• Behave mostly like non-metals

• But do have some metallic properties, most importantly they can conduct electricity.

Metalloids

• Group of elements that rarely react and are stable.

Noble Gases (or inert gases)

1. Group VIII – The Noble Gases• All are colourless gases

• Occur naturally in the atmosphere

• Very stable

• Helium is safe and light, but the gases get heavier and more dense the further you go down the group.

Families of Importance

2. Group VII – The Halogens• Form ions with a charge -1• Found in nature as salts• Have coloured and poisonous vapours• Form diatomic molecules• As you move down the group, the atoms get

bigger and less reactive

Families of Importance

3. Group I – Alkali metals• Form +1 ions• Extremely reactive• Found in nature only as mineral salts• Have typical metallic properties• All alkali metals react violently with water,

producing an basic solution and hydrogen gas.

Families of Importance

4. Group II – The Alkaline Earths• Act in a similar but less reactive way as the

Group I elements

Families of Importance