Atoms and Elements Notes

Matter Anything that has mass and takes up space Made of atoms

Matter Proton: Neutron: neutral & in the nucleus Matter Atom Electron: Positive & in the nucleus Neutron: neutral & in the nucleus Matter Anything that has mass and takes up space Atom Smallest unit of matter Electron: Negative, tiny, & outside of the nucleus

ATOMS Smallest unit of matter. Atoms make up everything (that has mass and takes up space).

Protons (+) Determines the identity of the Element Represents the Atomic # Positively charged Nucleus Part of the atoms mass

Neutrons – No charge Neutral – No charge Nucleus Part of the atoms mass

Electrons (-) Negatively charged smallest particles Outside nucleus Found in the electron cloud Located in energy levels

Atomic Particle Size

Nucleus Center of the atom Made up of Protons and Neutrons Makes up the atoms MASS Positively Charged!

Electron Cloud Area around the nucleus where electrons are found. Negatively Charged

Energy Levels Levels within the electron cloud that hold a specific # of electrons. 1st level - 2 electrons 2nd level - up to 8 electrons 3rd level – up to 8 or 18

Valence Electrons Electrons on the outermost energy level of the atom. Determine the atoms chemical properties, including reactivity.

Atomic Structure Review Protons (+) make up the nucleus Neutrons (no charge) Make up the nucleus Electrons (–) Found in energy levels around the nucleus in the electron cloud

Atomic Number Top # on the periodic table # of protons in the atom

Chemical Symbol 1 or 2 letter abbreviation for an element name 1st letter Capitalized 2nd letter – always lowercase Helium - He

Atomic Mass Bottom # Mass of the atom Located in the nucleus Equal to Protons + Neutrons

Determining the # of subatomic particles in atoms Use the following A = P = E M – A = N Atomic # = Protons = Electrons Mass – Atomic # = Neutrons

Atom Models

Valence Electrons The electrons in the outermost energy level of the atom. What element is this? How many valence electrons does it have?

ELEMENTS All the atoms that make up our universe Identified by the atomic # (# of protons)

3 Main Groups on the Periodic Table

Metals Make up most of the elements All solid except Mercury Has luster (shiny) Good conductors of heat and electricity Malleable – hammered or shaped into thin sheets Ductile – stretched into wires

Metals

Nonmetals Usually gases or brittle solids Poor conductors of heat and electricity They are insulators Right side of the periodic table Only 17 nonmetals

Metalloids Called Semi-metals Share properties of both metals and nonmetals Located on the zig-zag line between the metals and nonmetals.

Groups/Families 18 groups Vertical Columns on the periodic table Same # of valence electrons Same chemical properties including reactivity Reactivity – Elements tendency to undergo chemical reactions

Periods 7 horizontal rows on the periodic table Consist of elements with the same number of electron levels.

Alkali Metals Group #1 All metals 1 Valence Electron Very reactive Most reactive – the only need to lose 1 valence electron in chemical bonds

Alkaline-Earth Metals Group #2 All Metals 2 Valence Electrons Very reactive but less than group #1. Only have to lose 2 valence electrons in chemical bonds

Valence Electrons Group 1 – all elements have 1 valence electron have 2 valence electrons

Transition Metals Groups # 3-12 All metals 1 or 2 valence electrons Less reactive than group #2 Also contains lanthanide and actinide series

Groups # 13-16 Elements change from metals to nonmetals and include the metalloids. Atoms have 10 fewer valence electrons than the group #. Boron Group #13 - 3 valence electrons Carbon Group #14 - 4 valence electrons Nitrogen Group #15 - 5 valence electrons Oxygen Group #16 - 6 valence electrons

Halogens Group 17 All nonmetals 7 valence electrons Very reactive Only need to gain 1 more electron for a total of 8!

Noble Gases/Inert Gases Group # 18 All nonmetals 8 valence electrons - except helium only has 2. Unreactive Have a full outer electron level 2 on the 1st level 8 on the 2nd level

Hydrogen stands alone 1 valence electron Very reactive Colorless, odorless gas at room temperature. Low density Reacts explosively with Oxygen