Atom NotesAtom Notes

– – the science that the science that studies the properties of studies the properties of substances and how they react substances and how they react with each other.with each other.

Chemistry

Review NotesReview Notes

Matter is made of particles Matter is made of particles called atoms that are too small called atoms that are too small to see with the eyes.to see with the eyes.

Matter can not created or Matter can not created or destroyed.destroyed.

Matter can be an element, a Matter can be an element, a compound, or a mixture.compound, or a mixture.

Review NotesReview Notes

Elements are the simplest Elements are the simplest substances.substances.

Matter can undergo physical and Matter can undergo physical and chemical changes.chemical changes.

How small are atoms?How small are atoms?

There are 2 x 10There are 2 x 102222 zinc and copper zinc and copper atoms in an ordinary penny! atoms in an ordinary penny!

That is That is 20,000,000,000,000,000,000,000!20,000,000,000,000,000,000,000!

Types of Atoms in Types of Atoms in Earth’s CrustEarth’s Crust

Hydrogen makes up about 90% Hydrogen makes up about 90% of the total mass of the universe.of the total mass of the universe.

In Earth’s crust, In Earth’s crust, 47%47% OxygenOxygen 28%28% SiliconSilicon 12%12% Other elementsOther elements 8% 8% AluminumAluminum 5%5% IronIron

Types of Atoms in Types of Atoms in Living ThingsLiving Things

Living things are mostly oxygen, Living things are mostly oxygen, carbon, hydrogen, and nitrogen, carbon, hydrogen, and nitrogen, plus more than 20 other elements.plus more than 20 other elements.

In humans, In humans, 61%61% OxygenOxygen 23%23% CarbonCarbon 10%10% HydrogenHydrogen 3% 3% NitrogenNitrogen 3%3% Other elementsOther elements

Names and Symbols of Names and Symbols of ElementsElements

Elements get their names in Elements get their names in different ways. different ways.

Elements can be named from Elements can be named from people, places, and Greek words.people, places, and Greek words.

Each element has a unique Each element has a unique symbol.symbol.

Elements have unique atomsElements have unique atoms

Every atom of a specific element, Every atom of a specific element, such as silver, is similar to every such as silver, is similar to every other atom of the same element.other atom of the same element.

Every atom of a specific element Every atom of a specific element is different from an atom of a is different from an atom of a different element.different element.

How? It’s all about the structure How? It’s all about the structure of the atom!of the atom!

What is inside an atom?What is inside an atom?

Nucleus Nucleus – the dense center of – the dense center of the atom made of protons and the atom made of protons and neutronsneutrons

pp

pp

p

p ProtonsNeutrons

Nucleus

Let’s be positive!Let’s be positive!

Protons Protons –– positively charged positively charged particles in the nucleus: p+particles in the nucleus: p+

pp

pp

p

p ProtonsNeutrons

Nucleus

Protons have a mass of one amuProtons have a mass of one amu

I don’t get a charge out of youI don’t get a charge out of you

Neutrons Neutrons - neutral particles in - neutral particles in the nucleus: nthe nucleus: n00

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pp

p

p ProtonsNeutrons

Nucleus

Neutrons have a mass of one amuNeutrons have a mass of one amu

What is on the outside?What is on the outside?

ElectronsElectrons – Negatively charged – Negatively charged particles that orbit the nucleus particles that orbit the nucleus in energy levels: e-in energy levels: e-

pp

pp

p

p ProtonsNeutrons

Nucleus

Electrons

Shell

Neutral atoms have balance!Neutral atoms have balance!

In neutral atoms the # of protons In neutral atoms the # of protons equals the # of electrons, but the equals the # of electrons, but the neutrons can be differentneutrons can be different

pp

pp

p

p ProtonsNeutrons

Nucleus

Electrons

Shell5

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Forces in the Atom, part 1Forces in the Atom, part 1

Gravity:Gravity: pulls objects pulls objects toward one another. It toward one another. It depends on the mass of depends on the mass of

the object and how the object and how far apart the far apart the

objects areobjects areThe force of gravity The force of gravity in atoms is very in atoms is very small.small.

Forces in the Atom, part 2Forces in the Atom, part 2

Electromagnetic Electromagnetic Force:Force: protons protons and electrons and electrons are attracted to are attracted to each other each other because they because they have opposite have opposite chargescharges

Forces in the Atom, part 3Forces in the Atom, part 3

Strong Force:Strong Force: protons protons repel each other repel each other because they have because they have the same charge. the same charge. The strong force The strong force overcomes this overcomes this repulsion to hold the repulsion to hold the nucleus together.nucleus together.

Forces in the Atom, part 4Forces in the Atom, part 4

The Weak ForceThe Weak Force: is : is an important force an important force in radioactive in radioactive atoms. atoms.