The Atom What defines the property of a substance
WHAT MAKES UP MATTER? The one thing that makes up all things in the universe is: ATOMS
WHAT ARE ATOMS? Atom: smallest part of an element that can be identified as the element. (can be found on periodic table) For instance water (H 2 O), it can be broken down to 2 hydrogen atoms and 1 oxygen atom.
DEMOCRITUS
Democritus: the first person to suggest the idea of atoms. He was a Greek philosopher who lived more than 2400 years ago. He used the word “atom” which means cannot be divided.
JOHN DALTON
DALTON’S ATOMIC THEORY In the early 1800’s, stated an atomic theory of matter. Dalton’s theory was the beginning of the modern theory of atoms.
DALTON’S ATOMIC THEORY All elements are composed of atoms. Atoms cannot be divided or destroyed. Atoms of the same element are exactly alike. Atoms of different elements are different. The atoms of 2 or more elements can join together to form compounds.
TODAY We know that atoms define the chemical properties of different substances Atoms can be divided into smaller particles These particles help to define the characteristics of the atom
PARTS OF THE ATOM Electron: negatively charged particle. Neutron: neutral particle. Proton: positively charged particle. Nucleus: center, or core, of an atom.
PARTICLES OF THE ATOM Proton: Mass: x g Atomic mass: 1 Charge: +1 Location: Nucleus
PARTICLES OF THE ATOM Neutron: Mass: x g Atomic mass: 1 Charge: 0 Location: Nucleus
PARTICLES OF THE ATOM Electron: Mass: 9.11 x g Atomic mass: 0 Charge: -1 Location: Space around the nucleus The electron is so small compared to the other particles, it is given an atomic mass of 0
PARTS OF THE ATOM
HOW DO ELECTRONS ORBIT THE NUCLEUS In your notebook, draw how you think the electrons go around the nucleus In addition, HOW many elections go in each section?
BOHR MODEL The model most of you suggested is called the Bohr model of the atom Using the periodic table, you can figure out how many electrons “orbit” in each “shell” of the atom We will be discussing the “electron configuration” later in the quarter