Chapter 1- The Atom Flashcards
(22 cards)
Who is J.J. Thomson?
He use the cathode ray tube to find that the ray is formed by negatively charged particles (electrons)
What does the Plum Pudding Model show, and who was it created by?
- It was created by JJ Thompson
- shows the mass of the Adam is evenly distributed and positively charged taking up space not occupied by the electrons
Who is Ernest Rutherford?
- Created a model of an atom that had a nucleus
- he use the gold foil experiment it shows that the nucleus had a positive charge and the atom is mainly made up of empty space
What is the Planetary Model?
- also called the Bohr’s model
- Showed a center, nucleus, and rings of orbiting electrons
What are Valence electrons?
The outermost electrons located in the Valence shell
What is the Wave-Mechanical-Model?
Shows that atom with a nucleus and orbitals
What are the mass of protons?
1.67 x 10 ^-24 g
What is the definition of atomic number?
The number of protons in the nucleus of an atom
What are isotopes?
Atoms of the same element that have different numbers of neutrons or different mass numbers
What is Dalton’s Theory of the atom?
- All elements are composed of indivisible atoms
- All atoms of a given element are identical
- Atoms of different elements are different that is they have different masses
- Compounds are formed by the combination of atoms of different elements
What is the definition of atomic masses?
The average mass of all isotopes in a sample of an element
What is the ground state?
When electrons occupy the lowest available orbitals
What is the excited state of an electron?
When electrons absorb energy and temporarily moved to a higher energy level
How long does an excited electron stay at the higher energy level?
Only stays at the higher energy level temporarily
What is a Homogeneous matter?
A material that has a uniform composition throughout
Example: sugar water
What is heterogeneous matter?
Materials made up of parts with different chemical and physical properties
Varying composition
not uniformly mixed or dispersed
What is the definition of Pure Substance and the two types?
A pure substance is a matter that has the same composition throughout the sample
The two types are elements and compounds
What are Elements?
Elements are substances that cannot be broken down or decomposed into simpler substances by chemical means
What are Compounds?
Compounds are composed of two or more elements that are chemically combined it in a definite proportions by mass
What is the Law of Definite Proportions?
The statement that types of atoms in a compound exist in a fixed ratio
What is the definition of mixtures?
Mixtures are combinations of two or more pure substances that can be separated by physical needs and not have fixed compositions
What is an example of a mixture?
Iron and sulfur when mixed loses their own properties
