4.1 Studying Atoms

Plum pudding model

Thomson's model of an atom that shows negative charges (Electrons) are scattered throughout the atom with a positively charged mass of matter

4 main components of Dalton's theory-

-All elements are composed of atoms -All atoms of the same element have the same mass, and atoms of different elements have different masses -Compounds contain atoms of more than one element -In a particular compound, atoms of different elements always combine in the same way.

Dalton's Atomic Theory

1) elements are composed of atoms. 2) atoms of same element are identical, but differ from other elements. 3) elements can mix together 4) atoms only change when mixed with other elements

Dalton's theory

All matter is made up of individual particles called atoms, which cannot be divided,

Who did not think there was a limit to the number of times matter could be divided

Aristotle

(English teacher)Dalton's Theory of the Atomic Theory was known as

Billiard Ball Theory

Modern day way to think of Thomson's model of an atom

Chocolate chip ice cream chocolate chips are negative charges spread throughout while the ice cream is the positive balance (charge)

______________ gathered evidence for the existence of atoms by measuring the masses of elements that combine when compounds are formed

Dalton

Thomson revised _________ model to account for these subatomic particles

Dalton's

Who first named the atom

Democritus

Who believed that all matter consisted of extremely small particles that could not be divided

Democritus (philosopher)

Aristotle thought that all substances were built from these four elements

Earth, wind, fire and water That were a combo of 4 qualities hot, cold, dry, and wet Water= wet and cold Fire = hot and dry

Who discovered in 1899 that uranium emits fast moving particles that have a positive charge?

Ernest Rutherford

Who used an electric current to learn more about atoms?

J J Thomson

Who concluded that a gas consists of individual particles

John Dalton from England

Besides discovering the nucleus the Gold Foil Experiment discovered

Most of the mass of an atom is found in the nucleus

Rutherford concluded (from the Gold Foil experiment) that the positive charge of an atom is _________ evenly spread throughout the atom. It is concentrated in a ____________________________.

NOT VERY SMALL, CENTRAL AREA

ACCORDING TO RUTHERFORD'S MODEL, ALL OF THE ATOM'S POSITIVE CHARGE IS CONCENTRATED IN ITS _________

NUCLEUS

What is the dense, positively charged mass located in the center of an atom Discovered by Rutherford

NUCLEUS

What did Dalton discover about compounds?

No matter how large or small the sample, the ratio of the masses of the elements in the compound is always the same.

True or False Because Thomson's model no longer explained all the evidence, Rutherford proposed a new atom model

TRUE

What was the name of the experiment Rutherford's student Marsden conducted?

The Gold Foil Experiment

__________________ discovery changed how scientists thought about atoms. Before his experiments, the accepted model of the atom was a solid ball of matter that could not be divided into smaller parts.

Thomson

Who's experiments provided the first evidence that atoms are made of even smaller particles?

Thomson

True or False Dalton's theory was revised because of new discoveries by other scientists

True

True or False Even with a microscope, scientists cannot see the structure of an atom.

True

What did the model that Dalton created to represent elements/atoms look like?

Wood spheres

What did Rutherford call the fast moving particles in uranium that have a positive charge called?

alpha particles

A flow of charged charged particles is called ______

an electric current

In Marsden's experiment (The Gold Foil) alpha particles whose paths were deflected must have come close to __________________________

another charged object.

Objects with opposite charges _________ or _______

attract or pull together

Dalton found that Compounds have ____________ compositon

fixed

Some charged particles can _______ from one location to another

flow

Marsden saw that the closer the alpha particles came to this mystery charged object (nucleus) the __________ the deflection was

greater

An Atom is ___________

neutral )it has neither a negative nor a positive charge

Thomson concluded that

particles in the beam had a negative charge because they were attracted to the positive plate

Based on the behavior that certain materials when rubbed can either attract or repel other materials are said to have either a ____________ or _________ electric charge

positive or negative

Objects with like charges ___________, or ___________.

repel or push apart

When some materials are ______ they gain the ability to attract or repel other materials

rubbed

What did Rutherford ask his student Marsden to experiement on?

to find out what happens to alpha particles when they pass through a think sheet of gold.