What is an atom?What is an atom?

They are the building They are the building blocks of all matter.blocks of all matter.

Everything is made of Everything is made of atoms.atoms.

Example: LegosExample: Legos

What makes up an atom?What makes up an atom?

Protons- particles that Protons- particles that have a positive charge.have a positive charge.

Neutrons- particles that Neutrons- particles that have a neutral charge.have a neutral charge.

Protons and Neutrons Protons and Neutrons form the Nucleus of the form the Nucleus of the atom.atom.

Electrons- particles that Electrons- particles that have a negative charge.have a negative charge. Electrons

Protons and Neutrons

Nucleus

What is on a periodic table?What is on a periodic table?

Atomic number- Atomic number- number of protons in number of protons in the nucleus of an atom.the nucleus of an atom.

Atomic SymbolAtomic Symbol Mass number- is equal Mass number- is equal

to the number of to the number of protons and neutrons protons and neutrons that make up its that make up its nucleus.nucleus.

Element NameElement Name

O8

16Oxygen

Link

What is an isotope?What is an isotope? Atoms of the same element with different Atoms of the same element with different

numbers of neutrons in the nucleus.numbers of neutrons in the nucleus. Having a different number of neutrons will Having a different number of neutrons will

not change the element, but it will change not change the element, but it will change the mass.the mass.

Carbon 12

Carbon- 6 protons + 6 Neutrons = Mass Number of 12

Carbon 14

Carbon- 6 protons + 8 Neutrons = Mass Number of 14Isotopes

What are isotopes used for?What are isotopes used for?

Medical purposesMedical purposes Determining the age Determining the age

of ancient objectsof ancient objects Example: Carbon-14 Example: Carbon-14

is used for carbon or is used for carbon or radioactive dating of radioactive dating of ancient objectsancient objects

How do atoms combine?How do atoms combine?

Sharing electrons in Sharing electrons in there outermost there outermost portion of their portion of their electron cloud. This is electron cloud. This is called a covalent called a covalent bondbond

Example- HExample- H220 (water)0 (water)

By losing or gaining By losing or gaining electrons. This is electrons. This is called an Ionic bondcalled an Ionic bond

Example NaCl (salt)Example NaCl (salt)

Sharing ElectronsSharing Electrons

HH220- 2 atoms of 0- 2 atoms of hydrogen can share hydrogen can share electrons with 1 atom electrons with 1 atom of oxygen to form 1 of oxygen to form 1 molecule of watermolecule of water

Hydrogen has 1 Hydrogen has 1 electron in its outer electron in its outer shell to be shared.shell to be shared.

Electrons being shared

Gaining and Losing ElectronsGaining and Losing Electrons

When an atom loses electrons, it has more When an atom loses electrons, it has more protons that electrons so the atom is protons that electrons so the atom is positively charged.positively charged.

When an atom gains electrons, it has When an atom gains electrons, it has more electrons than protons so the atom is more electrons than protons so the atom is negatively charged.negatively charged.

IONSIONS

Sodium (Na) atom Sodium (Na) atom loses an electron and loses an electron and becomes a positively becomes a positively charged ION.charged ION.

Then it comes close Then it comes close to a negatively to a negatively charged Chlorine (Cl) charged Chlorine (Cl) ION to form NaCl.ION to form NaCl.

Na + Cl = NaClNa + Cl = NaCl

What is an Ion?What is an Ion?

Electrically Charged Electrically Charged AtomsAtoms

They are attracted to They are attracted to each other when they each other when they have opposite have opposite charges.charges.

The atom has either The atom has either gained or lost an gained or lost an electron making it a electron making it a charged atom.charged atom.

What is the difference between What is the difference between a compound and a mixture?a compound and a mixture?

A new substance that A new substance that forms when elements forms when elements combine.combine.

Cannot be separated Cannot be separated back into the individual back into the individual elements by physical elements by physical means. means.

Example: Hydrogen and Example: Hydrogen and Oxygen, which are gases, Oxygen, which are gases, combine to form water. combine to form water. The gases cannot be The gases cannot be separated back.separated back.

Do not change into Do not change into something new when something new when mixed together.mixed together.

Can be separated back Can be separated back into their individual into their individual substances.substances.

Example: In trail mix, the Example: In trail mix, the raisins and peanuts don’t raisins and peanuts don’t change into a new change into a new

substancesubstance. It’s easy to . It’s easy to separate them back.separate them back.

Compound Mixture