Ch 3 Outline:
Pg. 61 Once upon a time a Chinese cook combined charcoal with two other common Chinese ingredients. It ended with an explosion of sparks. Even if that story is false, most everyone agrees that fireworks originated from China.
Pg. 62 This page includes an image of 48 iron atoms forming a “corral” around a single copper atom.
Pg. 63 Atoms are like a wrapped birthday present, you want to investigate it, but you cannot see it easily.
Pg. 64 The term atoms means “cannot be divided”. Early philosophers used reasoning, debating, and discussion to prove their theories. Chemistry is the study of matter. Little was known about atoms even 500 years ago. Even today, with our most powerful microscopes, we are not able to see atoms. It is
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65 During the eighteenth century scientists began debating the existence of atoms again. All matter is made of elements. An element is matter made of atoms of only one kind. John Dalton combined the idea of atoms and elements together in the nineteenth century. His ideas: 1. Matter is made up of atoms, 2. atoms cannot be divided into smaller pieces, 3. all the atoms of an element are exactly alike, and 4. different elements are made of different kinds of atoms. John Dalton’s theory was tested in the later half of the nineteenth century.
Pg. 66 A piece of metal that can conduct energy is called an electrode. One electrode (the cathode) has negative charge; another (anode) has a positive charge.
Pg. 67 Negatively charged particles are now called electrons. Particles smaller than the atom do exist. Opposite charges attract each other.
Pg. 68 Thomson pictures a model of an atom as a sphere of positive charge wit the negatively charged electrons were spread evenly among the positive charge. Not all atoms are neutral. The number of electrons within an element can vary. Alpha particles are fast-moving, positively charged bits of matter.
Pg. 69 Some alpha particles were veering off at large angles during Rutherford’s experiment.
Pg. 70 Large changes in direction were not expected. A proton is a positively charged particle present in the nucleus of all atoms. The rest of each atom is simply empty space occupied by the atom’s almost mass less
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79 The radioactive decay of unstable atoms goes on at a steady pace, unaffected by conditions such as weather, pressure, magnetic, or electric fields, and even chemical reactions.
Pg. 80 Scientists use Carbon-14 to detect how old a living (but now dead) organism is. This is also known as radioactive decay. Radioactive decay produces radioactive waste.
Pg. 81 Tracer elements are synthetic. Elements with the atomic numbers 93 to 112, and 114 have been made in this way.
Pg. 82 Very small amounts of radioactive substances, called radioisotopes or “tracer elements”, can be used to diagnose disease.
Pg. 83 Isotope iodine-131 is used to diagnose problems with the thyroid. Tracer elements such as phosphorus-32 are injected into the root system of a plant.
Pg. 84 The decay rates of most radioactive isotopes range from milliseconds to billions of years.
Pg. 85 Using scientific methods determine whether you can predict individual atom half-lives.
Pg. 86 One cloudy day in the spring of 1896, physicist Henri Becquerel was unable to complete the day’s planned work requiring the Sun as the primary energy source. He later discovered uranium emits
The short half-life means it takes all of 20.39 minutes before the Carbon 11 tracer decays into boron 11. 11b is a chemically stable radioisotope of boron. Patient is only radioactive for a short amount of time.
In "Energy Story" uses an explanation of atoms and tells us the parts of an atom and its structure. In the text it
physics. The work of Ernest Rutherford, H. G. J. Moseley, and Niels Bohr on atomic
Metals contain a sea of electrons (which are negatively charged) and which flow throughout the metal. This is what allows electric current to flow so well in all metals. An electrode is a component of an electric circuit that connects the wiring of the circuit to a gas or electrolyte. A compound that conducts in a solution is called an electrolyte. The electrically positive electrode is called the anode and the negative electrode the cathode.
An atom, by definition, is the smallest part of any substance. The atom has three main components that make it up: protons, neutrons, and electrons. Protons and neutrons are within the nucleus in the center of the atom. The electrons revolve around the nucleus in many orbitals. These orbitals consist of many different shapes, including circular, spiral, and many others.
Attempts to organize the elements began in the late 1800’s. At this time, about sixty elements were known. Much advancement would have been impossible if the basic model of the atom was discovered. Great progress came from Dmitri Medeleev – a Russian chemist. His first draft of a periodic table was only the product of him attempting to summarize his knowledge of the elements. Although not all of Medeleev’s ideas were one-hundred percent accurate, they created a solid base to build upon. Marie and Pierre Curie; a married couple from Paris were successors of Medeleev. Their interests were radioactivity and discovered radium. The true pioneers of the periodic table were Ernest Rutherford and James Chadwick. Rutherford formed the hypothesis that, “An atom must have a concentrated positive center charge that contains most of the atom’s mass.” Following Rutherford, Chadwick exposed a segment of the nucleus that was had no charge: the neutron. With the basic knowledge of the structure of an atom, the tedious work of putting the rest of the puzzle together continued.
To understand what a radioactive isotope is a basic understanding of the atom is necessary. Atoms are comprised of three subatomic particles : protons, neutrons and electrons. Protons and neutrons bind together to form the nucleus of the atom, while the electrons surround and orbit the nucleus. Protons and electrons have opposite charges and therefore attract one another (electrons are negative and protons are positive, and opposite charges attract), and in most cases the number of electrons and protons are the same for an atom (making the atom neutral in charge). The neutrons are neutral. Their purpose in the nucleus is to bind protons together. Because the protons all have the same charge and would naturally repel one another, the neutrons act as "glue" to hold the protons tightly together in the nucleus.
The theory of quantum mechanics has divided the atom into a number of fundamental sub-atomic particles. Although the physicist has shown that the atom is not a solid indivisible object, he has not been able to find a particle which does possess those qualities. Talk of particles, though, is misleading because the word suggests a material object. This is not the intention for the use of the word in quantum physics. Quantum particles are, instead, representations of the actions and reactions of forces at the sub-atomic level. In fact, physicists are less concerned with the search for a material particle underlying all physical objects and more interested in explaining how nature works. Quantum theory is the means that enables the physicist to express those explanations in a scientific way.
Uuq-292 lost 3 neutrons, and afterwards the resulting isotope decayed further by alpha emission. 24494Pu + 4820Ca 292114Uuq 289114Uuq + 3(10n), this claims that superheavy elements can be made in the laboratory.
The Atomic Theory began in roughly 400BC with Democritus in Ancient Greece and is universally believed to be correct today. Democritus who was born in 460 BC and died 370 BC and is known as the father of modern science. Democritus proclaimed that everything is made up of atoms. He continued his theory to say that atoms will always be in motion, between atoms there is empty space, atoms are unbreakable, there are an infinite number of atoms all different sizes and shapes. He also said that iron atoms are solid and strong and have hooks to lock them together, water atoms are smooth and slippery, salt atoms have sharp jagged edges because of its taste and air atoms are light and spiralling.
Dalton’s atomic theory says that each element contained its own number of atoms. Each element had its own size and weight. Dalton’s idea said that all things are made of small bits of matter this bits of matter where too small to be seen even with a microscope. Scientist began to think these small bits of matter where responsible for chemical changes. They thought that when these bits of matter combined a chemical change took place. Dalton assumed that there was a special pattern in the elements and was partly responsible for the periodic table.
The idea of the atom started all the way back from the ancient Greece. What is sad about this is that one philosopher’s idea it was rejected by the rest of the philosophers of the time. Philosophers like Aristotle. The ancient Greeks did not have all the modern technology we have now and were not equipped to test their atomic theory. The theory they had hypothesized was if you keep dividing something, the smallest living thing had to be an atom.
Things are very different from each other, and can be broken down into small groups inside itself, which was then noticed early by people, and Greek thinkers, about 400BC. Which just happened to use words like "element', and `atom' to describe the many different parts and even the smallest parts of matter. These ideas were around for over 2000 years while ideas such as `Elements' of Earth, Fire, Air, and Water to explain `world stuff' came and went. Much later, Boyle, an experimenter like Galileo and Bacon, was influenced much by Democritus, Gassendi, and Descartes, which lent much important weight to the atomic theory of matter in the 1600s. Although it was Lavoisier who had divided the very few elements known in the 1700's into four different classes, and then John Dalton made atoms even more believable, telling everyone that the mass of an atom was it's most important property. Then in the early 1800's Dobereiner noted that the similar elements often had relative atomic masses, and DeChancourtois made a cylindrical table of elements to display the periodic reoccurrence of properties. Cannizaro then determined atomic weights for the 60 or so elements known in the 1860s, and then a table was arranged by Newlands, with the many elements given a serial number in order of their atomic weights, of course beginning with Hydrogen. That made it clear that "the eighth element, starting from a given one, is a kind of a repeat of the first", which Newlands called the Law of Octaves.
What is radioactivity? Radioactive isotopes are heavy nuclei of certain elements having extra neutrons. The extra neutrons in their nuclei cause them to be unstable so the nuclei break up spontaneously, emitting alpha, beta and gamma radiations. For example,
John Dalton was one of the first men to say that there is a possibility of matter to be made up of small particles. He reviewed a Greek philosophers idea of the atom and with experimenting he came up with his Dalton's Postulates state that all matter is composed of small, indivisible particles called atoms. All atoms of a given element are identical in mass and properties. Atoms are not created, destroyed, or converted into other kinds of atoms during chemical reactions; they are simply rearranged into new compounds. Compounds are formed by a combination of two or more atoms in definite arrangements in the ratio of small whole numbers.John Dalton later proposed the Law of Multiple Proportions. This law