Unit 2 Flashcards
What was John Dalton’s discovery?
All matter is made of atoms. Atoms are too small to see, indivisible and indestructible. All atoms of a given element are identical.
What was J.J Thompson’s discovery?
Discovered the negative electron, and predicted that there also must be a positive particle to hold the electrons in place.
What was Ernest Rutherford’s discovery?
Discovered the nucleus of an atom and named the positive particles in the nucleus “protons”. Concluded that electrons are scattered in empty space around the nucleus.
What was James Chadwick’s disocvery?
Discovered that neutrons were also located in the nucleus of an atoms and that they contain no charge.
What was Neils Bohr’s discovery?
Concluded that electrons are located in planet-like orbits around the nucleus in certain energy levels.
What is the modern atomic theory?
Electrons do not orbit the nucleus in neat planet-like orbits but move at high speeds in an electron cloud around the nucleus.
What is found in the nucleus of an atom?
Protons and neutrons
What is mass?
The amount of matter in an object
What is volume?
The amount of space an object takes up
Density is an intensive physical property. True or false?
True
What is a pure substance?
A sample of matter that has both definite and constant composition with distinct chemical properties. (Example: Element)
What is a compound?
A substance composed of 2 or more elements in a fixed ratio. (type of pure substance)
What is a mixture?
A substance made of two or more pure substances
What is a Homogeneous Mixture?
mixture in which the composition is uniform throughout the mixture. (Example: Kool Aid)
What is a Heterogeneous Mixture?
a mixture in which the composition is not uniform throughout the mixture. (Example: Lemonade or Salad)
