States of matter and Atomic Structure Flashcards
(20 cards)
Define the word ‘matter’
a group of particles that are in random constant motion.
State 3 characteristics of solids
molecules are close together
definite mass
definite shape
What determines the weight of an object?
the gravity
Define the word ‘molecule’ and give one example.
a group of two or more atoms chemically bonded together. eg: oxygen/carbon dioxide
What is a compound?
a group of two or more different elements that are held by chemical bonds in a fixed ratio.
What are the 2 main differences between a compound and a molecule?
a) a compund is made of elements while a molecule is made of atoms
b) a compund has a definite composition/fixed ratio while molecules do not
Define the term ‘mixture’
two or more substances that are not chemically combined or that can be separated using physical means.
What is a ‘homogenous mixture’
a gas, liquid or solid misture that has the same proportions of its components throughout a given sample. eg: vinegar, water
What is a ‘heterogenous mixture’
a mixture in which the composition is not uniform throughout the mixture eg: oil and water
Define an ‘alloy’
A mixture in which at least 1 of the elements is a metal.
State the atomic structure of oxygen
Protons-8
Neutrons-8
Electrons-negligible
Which scientist is known for developing the atomic theory?
John Dalton
What does the Atomic Theory state
all mater is made of tiny particles
State two major contributions to the atomic model that JJ Thompson provided.
a)discovered the electron
b) discovered that charges within the atom were even
What was Ernest Rutherford majorly known for?
the gold foil experiment
What is the gold foil experiment?
A beam of alpha particles was aimed at a piece of gold foil. Most alpha particles passed through the foil, but a few were scattered backward. This showed that most of the atom is empty space surrounding a tiny nucleus.
Which scientist predicted the neutron?
Ernest Rutherford
What is ‘valency’
is the number of electrons an atom gains or loses to be in the octet state
Define” octet “
When an atom has a full shell consisting of 8 electrons in the outer shell.
