Matter, Atoms, Elements A chemistry review

What’s matter?  Matter is anything that has mass and volume  Mass is  Volume is  Matter is made up of atoms

Atoms  Atoms are the simplest form of matter  The structure of atoms determines the properties of matter  An atom has:  Nucleus  Electron cloud

Created by G.Baker An atom refresher  An atom has three parts:  Proton = positive ◦ Mass about 1 amu  Neutron = no charge ◦ Mass about 1 amu  Electron = negative ◦ Mass 1/1836 amu  The proton & neutron are found in nucleus  The electrons are in the electron cloud Picture from _03.gif

Elements  Elements are made of one kind of atom  Elements cannot be broken into simpler substances using normal chemical reactions  Elements cannot be broken into simpler substances using physical reactions  Periodic table of elements!

Created by G.Baker Periodic Table 8 O Oxygen 16 Atomic Number: Number of protons and it is also the number of electrons in an atom of an element. Element’s Symbol: An abbreviation for the element. Element’s Name Atomic Mass/Weight: Number of protons + neutrons.

 Atoms of an element don’t always have the same mass number  Protons are the same!  What’s different?  Isotopes are  Examples: Isotopes Isotope# p+# n o # e-At noMass no Hydrogen-1 Hydrogen-2 Hydrogen-3

LecturePLUS Timberlake9 Isotope notation Show the mass number and atomic number Give the symbol of the element mass number 23 Na sodium-23 atomic number 11

Atoms all Want: Full outer (valence) electron shell How do they get it? Atoms form compounds Compound: 2 or more atoms chemically bonded together Bond: Force holding atoms together Properties of compound are different from elements

Bonding 2 kinds of bond: Ionic Covalent All bonds happen so atoms can have full valence shell!

Covalent bonding Covalent bonding: Sharing electron pairs Between nonmetal atoms Makes molecules Sometimes more than one pair is shared Double bond Triple bond

Let’s look at an example! Hydrogen! Atno is Number of valence e- Is H happy? NO! What would make the valence shell full?

Here’s Oxygen! Atno is Number of valence e- Is O happy? NO! What would make O happy?

Bonding! H says let’s share! Another H also shares! Now everyone’s happy! We’ve made a compound!

Who’s going to share? Elements in groups and H Elements in group 17 and H with themselves

Ionic Bonding Ion: A particle with a charge Formed when: Atoms gain or lose e- Gain e- : become negative Lose e- : become positive Metal and nonmetal bond Metals: left side of periodic table Nonmetals: right side of periodic table

Forming Ions Let’s think about sodium! Atno is: Na

Forming Ions How about chlorine? Atno is

Forming Ions What happens? Na loses e- Becomes Na+ Cl gains e- Becomes Cl-

Forming Ions What happens? Na+Cl- Opposite charged ions are attracted!