# ATOMS Basic building blocks of matter. –Atoms make up everything (that has mass and takes up space).

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ATOMS Basic building blocks of matter. –Atoms make up everything (that has mass and takes up space).

Atomic Structure Protons – positively charged particles inside the nucleus. Neutrons – neutral particles inside the nucleus that have No charge. Electrons – negatively charged particles in atoms found around the nucleus.

A = P = E M – A = N Atomic # = Protons = Electrons Mass – Atomic # = Neutrons

Atomic Particle Size

Atomic Mass Unit - amu Unit of measurement for the mass of subatomic particles. –1 amu = 1.7 X 10 -24 They are TINY!!!.000000000000000000000017 grams –Proton = 1 amu –Neutrons = 1 amu –Electrons = almost zero (TINIEST particle with the least mass) –Most mass is in the nucleus with protons and neutrons –Otherwise atoms are mostly EMPTY SPACE

Atomic Number The number of protons inside the nucleus of the atom. Determines the element. Atoms have no charge because the # of protons (+ charge) is = to the # of electrons (- charge).

Mass Number/Atomic Mass The total number of protons and neutrons in an atoms nucleus. Protons + Neutrons = Mass Number Notice how massive the nucleus is compared to the rest of the atom

Atomic Mass The weighted average of the masses of all the naturally occurring isotopes of an element. Average of Protons + Neutrons of all an elements Isotopes = Atomic Mass

Electron Cloud Area around the nucleus where electrons are arranged. Energy Levels – Levels within the electron cloud that hold a specific # of electrons. –1st level - 2 electrons –2nd level - up to 8 electrons –3 rd level – up to 8 or 18

Valence Electrons The electrons in the outermost energy level (electron cloud). 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 – made into different shapes Ductile – made into wires

Metals

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

Metalloids Called Semi-metals Share properties of both metals and nonmetals

Groups/Families Columns of the periodic table Each element has the same # of valence electrons The elements share similar chemical and physical properties. They are each part of the same “family”

Periods 7 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 Group 2 – all elements 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 1 st level –8 on the 2 nd level

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

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