chapter 2 Flashcards
dont fail test
when did the first chemists live before
8000bc
what is the first age and were metals disovered or not
stone age and metals were not discovered
when did early chemists investigaste metals and liquid matter
between 600 bc and 1000bc
why was gold valued
becuase of its properties,It has attractive colour and lustre, and it didn’t tarnish. Its softness made it easy to shape into detailed designs, form into wire, and beat into sheets. Because it is so soft, however, gold could not be used for tools or weapons.
why was copper valued
Copper became valuable because it could be used to make pots, coins, tools, and jewellery. It was early chemists asking questions that led to an understanding of copper’s properties and how the material could be controlled. A piece of natural, untreated copper is brittle, that is, it breaks easily.
why was copper so big and used after the stone age
when copper is heated, it becomes very useful because it can be rolled into sheets or stretched into long wires. (
when was the copper age
4500 bc
Later experimenting with copper (about 4500 B.C.) led to the creation of a hard, strong material known as _______
bronze
what is produced when copper and tin are heated together
bronze
when did the iron age happen and who discovered it
Around 1200 B.C., a group of people in the Middle East called Hittites discovered how to extract iron from rocks and turn it into a useful material.
what is produced with iron to a even stronger materiel
carbon
what is created when iron and carbon are combined
a even stronger materiel called steel
Many cultures investigated the ways of extracting and using different types of _______
liquids
whats a example of using different juices and oils
(using liquid matter)
In ancient Egypt, human bodies were preserved after death by being wrapped in cloths soaked in natural pigments and resins from the juniper tree.
what describes the smallest particles that could NOT be broken further.
atomos (atoms)
meaning it cant be broken down further
when and who made the theory
that all material bodies are made up of indivisibly small “atoms.”
what is the atomic threory
all material bodies are made up of indivisibly small “atoms.”
when did democritus come up with this theory
400 bc
who is the greek philosipher arisotle and what did he theory
He stated that everything was made of earth, air, fire, and water. Because Aristotle was well known and well respected, his description of matter was preferred over Democritus’s description for 2000 years.
when did arisotle come up with the element theory
350 bc
who are alchemists
people who were part magician, part scientist.
today whats the study of alchemy called
pseudo-science (an activity that is not a real science because it includes the use of magic).
what did alchemists believe back then
Alchemists believed that it should be possible to change metals into gold. They were not interested in understanding the nature of matter.
what useful tools did alchemists invent to perform their expeirments
beakers and filters.
what did alchemist al-razi disover
plaster of Paris a material that today’s doctors still use to hold broken bones in place until they heal.
why are philosiphers and scientists different
Unlike the philosophers, early scientists based their theories on observations and experimentation.
what did robert boyle do
Robert Boyle experimented with the behaviour of gases. He was interested in what happened when gases were placed under pressure. He was also interested in determining the composition of gases and other substances.
through boyles experements what did boyle come to the conclusion of
Through his experiments and observations, Boyle became convinced that matter was made up of tiny particles, just as Democritus had suggested in about 400 B.C.
what did boyle belive in
Boyle believed that the tiny particles, existing in various shapes and sizes, would group together in different ways to form individual substances.
what did boyle feel the purpose of chemisty was
Boyle felt that the purpose of chemistry was to determine the types of particles making up each substance.
when did robert boyle experiment with gases
1660s
what did French scientist Antoine Laurent Lavoisier study
chemical interactions
when did he desover a system for naming chemicals
late 1780s
when did antoine start studying chemicals
1770s
why is this significant that he disovered a system for naming chemicals
This was significant, for now all scientists could use the same words to describe their observations. That made it easier to compare the results of their experiments.
Using his naming system, Lavoisier defined some of the substances discovered at that time, including
hydrogen, oxygen and carbon
Because of his experimental and theoretical work, Lavoisier is called the
“father of modern chemistry”
what was john daltons own theory of composistion of matter
Dalton suggested that matter was made up of elements.
what was john the first to do
He was the first to define an element as a pure substance that contained no other substances.
what was examples of pure substances
gold, oxygen and chlorine are example
what did theory did john come up with
Dalton also put forward the first modern theory of atomic structure.
whats the first modern theory of atomic structure
He stated that each element is composed of a particle called an atom. All atoms in a particular element, he said, are identical in mass, and no two elements have atoms of the same mass.
whats daltons model called
Dalton’s model is sometimes called the “billiard ball model” because he thought of the tiny atoms as solid spheres.
whats a example of daltons atomic theory
all oxygen atoms have the same mass, which is different from the mass of chlorine atoms
what did british physicist experiment
experimenting with cathode rays, concluded that the rays were made up of streams of negatively charged particles.
what did jj find out using this cathode ray tube experiment
He showed that these particles were much smaller in mass than even a hydrogen atom. He named them electrons.
what is the raisin bun method
He described the atom as a positively charged sphere in which negatively charged electrons were embedded like raisins in a bun.
what did Japanese physicist Hantaro Nagaoka do
refined the model of the atom further. In his model, the atom resembled a miniature solar system.
describe his model
At the centre of the atom was a large positive charge. The negatively charged electrons orbited around this charge like planets orbiting around the Sun.
did scientists back then (1904)
Most scientists of the day did NOT agree with this model because existing theories could not explain it.
where did the support for the Nagaoka model and the idea of a central nucleus came from
British scientist Ernest Rutherford
using thompsons model what experiments did rutherfold conduct
shot positively charged particles through thin gold foil.
what did rutherfold predict would happen to the particles
predicted that all the high-speed particles would pass straight through the foil without being affected by the gold atoms.
what instead happned to the particles in rutherfolds experment
Instead, the results showed that while most particles did behave as predicted, some were greatly deflected.
what did rutherfold suggest after all these experments
He suggested that atoms were mainly empty space through which the positive particles could pass, but at the core was a tiny positively charged centre. This he called the nucleus
Rutherfold also calculated that the necleus was only about 1/____ the size of an atom
10 000
what did Neils Bohr ( who was working with rutherfold) suggest
electrons do NOT orbit randomly in an atom.
how did bohr say they move
Bohr said that they move in specific circular orbits, or electron shells, as shown in.
He thought that electrons jump between these shells by gaining or losing energy
what did james chadwick disover
Chadwick discovered that the nucleus contains positively charged particles called protons, and neutral particles called neutrons.
what is different between neutons and protons (have same mass)
neutrons have no electric charge
what is the quantum mechanics model
The quantum mechanics model of the atom describes electrons as existing in a charged cloud around the nucleus.
