Download Chapter 3, Section One - Bismarck Public Schools

Chapter 3, Section One
The Atoms Family!
What is an Atom?
•Ancient Greeks asked the question…
–If we were to cut matter (ie a carrot) into smaller and smaller pieces,
what would be the smallest piece possible?
–The answer? The atom.
–Word atom comes from atomos.
•Means “to cut”
What is an Atom?
•What we know today…
–Atoms make up elements such as oxygen, nitrogen, and helium.
•Check out your periodic table!
–Atoms are the smallest part of an element that still has all the same
properties of an element.
What is an Atom?
•Today, scientists believe the following about atoms….
•All elements are composed of atoms.
•Atoms of the same element are exactly the same.
•Atoms of different elements are different.
•Compounds are formed by the joining of atoms of two or more elements
The Atoms Family
•Atoms are made of three main particles
–Electrons
–Protons
–neutrons
The Atoms Family
•Protons
–Found in nucleus of the atom
–Positive charge
–Mass of 1 atomic mass unit (amu)
•Neutrons
–Also found in nucleus of an atom
–No charge
–Mass of 1 amu
•In a “normal” atom, the number of protons and neutrons is the same.
The Atoms Family
•Electrons
–Found orbiting the nucleus
•Like planets in the solar system
–Negative charge
–Mass is too small to measure
–In a “normal” atom, one electron per proton
The Atoms Family
•AN ATOM IS ALWAYS NAMED ACCORDING TO THE NUMBER OF
PROTONS.
–Carbon always has 6 protons, Oxygen always has 8, etc, etc
The Atoms Family
•Isotopes
–Atom with a different number of neutrons than electrons.
–Can have more or less neutrons.
–Does NOT change the charge of the atom.
–Written with a superscript
•Superscript shows the mass number.
–Mass number: the total of the protons and neutrons
–Units are amu
•Example: C13 (mass number 13)
•Carbon has 6 protons and 7 neutrons
–“normal” carbon has 6 protons and 6 neutrons C12
The Atoms Family
•Ions
–Atoms with a different number of electrons than protons
–Can have more or less electrons
–Leaves the atom with unbalanced positive and negative charges
•Results in a overall positive or negative charge.
The Atoms Family
•Ions
–If an atom loses an electron, what charge will it have? Why
The Periodic Table
•Periodic table includes the following information
–Atomic number
–Element symbol
–Element name
–Atomic mass
–Ionic charge
The Periodic Table
•Atomic Number
–The number of protons in the atom
–This number never changes
•Atomic Mass
–The average mass of the element and all of its isotopes
–Why is this not a whole number?
–The number is an average. Since there are more atoms with a mass of
10 amu, the number is closer to 10.
The Periodic Table
•Element Symbol
–Shorthand abbreviation for the element
•Element Name