ATOMS

Objectives What is an atom and its three subatomic parts? What are the charges of the three subatomic parts? How do you find atomic mass and the atomic number? Compound vs. element? What is an isotope?

How small is an atom? The basic unit of matter. the smallest unit. ‘unable to be cut’ Can it be seen? Is it living? 100 million atoms side by side is about the width of your pinkie!

What is an atom made of? 3 subatomic particles ◦Proton ◦Neutron ◦Electron

Proton POSITIVE PROTON (+) Located inside the nucleus Has a positive charge and contributes to the mass Mass AMU

Neutrons NEUTRAL NEUTRON ◦Located inside the nucleus ◦Has no charge but contributes to the mass ◦Mass AMU

Electrons Negative Charge ◦Orbits around the nucleus and is in constant motion. ◦They are attracted to the positive charged nucleus. ◦There are the same amount of protons as electrons. ◦Mass is too small to be included. ◦Mass AMU ◦(1/1836 th the mass of a proton)

Periodic Table Element- pure substance containing only one type of atom. We distinguish the elements based on protons, neutrons, and electrons.

Compound A substance formed by the chemical combination of 2 or more elements. The physical and chemical properties of a compound and usually very different from the elements in which they are formed. Sodium is a soft metal + poisonous chlorine = sodium chloride + =

compounds 2 or more elements Water = salt (sodium chloride) =

Atom = smallest unit of an element Molecule = smallest unit of compound

What does it mean? Atomic number= # of protons = # of electrons Atomic Mass= # of protons + number of neutrons Atomic mass

Isotopes Isotopes are atoms of the same element with the same number of protons but different number of neutrons. Some isotopes can give off radiation Isotopes are identified by their atomic mass.

Isotopes Helium-5 Atomic Mass = Atomic number (protons) = Number of neutrons = Helium-6 Atomic Mass = Atomic number (protons) = Number of neutrons = Helium-7 Atomic Mass = Atomic number (protons) = Number of neutrons = Helium-8 Atomic Mass = Atomic number (protons) = Number of neutrons =

Bonds What is the difference between a covalent bond and an ionic bond? What is an ion? What are valence electrons?

Chemical bonds Ionic – electrons are transferred from one atom to the next. Covalent- electrons are shared between atoms

Ionic bonds Formed when one or more electrons are transferred and ions (charged atoms)are paired. What is the charge of an electron? When sodium looses an electron it has a positive charge. Opposite ions attract!

Valence electrons The electrons in one atom that are able to form bonds with another atom. The closer the atom is to having 8 valence electrons, the more stable it is. Where are the valence electrons?

Ionic Bonds Bonds between a metal and nonmetal.

Covalent Bond Electrons are shared between atoms. 1 bond is when atoms share 2 electrons Nonmetal with nonmetal Neither atom is strong enough to pull an electron away from the other so they share.

Can an atom be broken? WKPrSc WKPrSc

Water - 3,000,000,000,000,000,000,000 water molecules in a single drop of water!

Properties of water 1. Polarity 2. Hydrogen bonds 3. Cohesion 4. Adhesion D_90

Hydrogen bonds The weak interaction between the slightly positive hydrogen and a negative atom (oxygen, fluorine, nitrogen)

Cohesion

Surface Tension

Adhesion