Chapter 1 Flashcards
— smallest “particle” of an element that remains the chemical properties of that element.
Think of as:
Billiard/Hard Balls
Indivisible & Indestructible
*Ultimate Chemical Property source *
Atom
— Greek philosopher
— determined atom was “uncuttable”
Democritus (400 BCE)
John Dalton (1803) assumed:
5 major assumptions
1) determined matter is made of atoms
2) all atoms of a given element are identical in mass & properties
*atoms of different elements have different mass & properties *
3) compounds are formed by combinations of two or more different kinds of atoms in whole # ratios.
4) chemical reactions — involve combination, separation, & replacement.
5) atoms not created, destroyed, divided, or converted.
John Dalton’s Work led to:
1) Law of Conservation of Matter (Lavoisier)
2) Law of Constant Composition (Proust)
3) Law of Multiple Proportions (Dalton)
— no change in mass accompanies a chemical reaction
Law of Conservation of Matter (Lavoisier)
— particular purified compound always contains same elements in the same ratio by mass.
Law of Constant Composition (Proust)
— when 2 elements form 2 compounds, the mass ratio in one element is a whole # x mass ratio in the other.
Ex) Hydrogen Peroxide: 1 part by mass H to 16 parts by mass O
Ex) Water: 1 part by mass H to 8 parts by mass O
Law of multiple proportions (Dalton)
Parts of an Atom
3 parts
1) Electrons — negative charges
2) Protons — positive charges
3) Neutrons — neutral/no charge
Radioactivity (Madame Curie: 1899)
3 major types:
1) Alpha Particles — nucleus
2) Beta Particles — electrons
3) Gamma Rays — electromagnetic radiation
— fundamental particle of electricity
— negative charge
Electrons
— equal but opposite charge of electrons
— +1 charge
Protons
— no charge
— discovered by James Chadwick (1932)
Neutrons
— Discovered by Rutherford, Geiger, & Marsden (1932)
— composed of protons and neutrons
— middle of the electron cloud
Nucleus
— each atom of an element has a # of protons.
Atomic Number
— total mass is slightly less than sum of masses of protons, electrons, neutrons
Mass Defect
