Chapter 7.1 Flashcards
The theory of atoms was originally proposed by who?
The atomic theory was originally proposed by the English John Dalton in 1810.
In 450 BC, the Greek philosopher Democritus said…?
By convention there is colour, by convention sweetness, by convention bitterness
How did Democritus propose hypotheses?
Democritus proposed hypotheses based on thought and reasoning.
What did French chemist Antoine Lavoisier discover?
Antoine Lavoisier found that compounds containing more than one element always had the same element.
example:
The compound now known as Carbon Dioxide used to be called ‘fixed air’. This was because it was heavier than air and did not allow other substances to burn in it.
What was discovered about ‘fixed air’?
The mass of oxygen in ‘fixed air’ was always 2.66 times the mass of carbon in the compound. This meant there was always the same ration of oxygen atoms to carbon atoms in the ‘fixed air’.
What did English scientist John Dalton state in 1810?
Matter, though divisible in an extreme degree, is nevertheless not infinitely divisible. That iss, there must be some point beyond which we cannot go in the division of matter… I have chosen the word atom to signify these ultimate particles.
What was John Dalton one of the first scientists to consider?
Dalton was one of the first scientists to consider the link between elements and atoms. He was the originator of what is now called the atomic theory.
What is one piece of evidence did John Dalton publish?
One of the pieces that Dalton published was the weights of atoms compared to that of the lightest atom, hydrogen. He assigned weights to atoms, such as ammonia (NH(small 3)), water (H(small 2)O), and carbon dioxide (CO(small 2)).
What did the piece of evidence John Dalton published lead to?
The evidence lead to Dalton proposing the law of simple multiple proportions. It means that when elements combine, they combine in simple ratios, like 2:1 as in water, 1:4 as in Methane, or 2:3 as in aluminium oxide. Dalton’s atomic theory gave scientists a way to explain evidence about atoms.
Why is a scientific theory written and how can they be used?
A scientific theory is written to explain existing evidence and observations. A good theory supported by a range of evidence can be used to make testable predictions.
What happened ever since John Dalton proposed his atomic theory?
Dalton’s atomic theory has been used to make predictions, and evidence that was not even available in Dalton’s time still supports his theory.
True or False - Elements cannot join together to form compounds.
False - Elements can join together to form compounds.
True or False - Water contains twice as much hydrogen as oxygen.
True - Water always contains twice as much hydrogen as oxygen.
True or False - When chemicals react with each other, the total mass of the chemicals change.
False - When chemicals react with each other, the total mass of the chemicals does not change.
True or False - Pure oxygen has the same properties wherever it is found on the Earth or even in space.
True - Pure oxygen has the same properties wherever it is found on Earth or even in space.d
