Chapter 1 * What is Chemistry? -it is the study of the composition of substances and the changes they undergo. * What are the 5 branches of chemistry? * Organic chemistry‚ inorganic chemistry‚ analytical chemistry‚ physical chemistry‚ biochemistry. * What is the difference between a theory and law? -a theory is a thoroughly tested explanation of why experiments give certain results. A scientific law is a concise statement that summarized the results of a broad spectrum of observations
Premium Atom Chemistry Electron
protons‚ neutrons‚ and electrons (as seen in the Helium atom below). Other particles exist as well‚ such as alpha and beta particles (which will be discussed later on). Most of an atom’s mass is in the nucleus‚ a small dense area at the center of every atom formed by nucleons. Nucleons are protons and neutrons. All of the positivity of an atom is contained in the nucleus‚ because the protons have a positive charge. Neutrons are neutral‚ meaning they have no charge. Electrons‚ which have a negative
Free Atom Electron Chemical bond
GREAT DISCOVERIES CHANGE LIVES Do you like watching television? I love it. I do not know what would I do if televisions did not exist. It is interesting‚ in several years‚ they have become a huge part of our lives‚ our indispensables. J.J. Thomson was inspired by some scientists and he provided us the opportunity of having televisions in our lives. Also other scientists improved his thoughts and experiments which leaded to the invention of the television afterwards. It is not that simple of course
Premium Atom Cathode ray tube Electron
Since the ancient times‚ people like the Greeks were acknowledged of the existence of elements‚ but only knew of common ones like gold‚ tin‚ and copper. It wasn’t until the middle of the nineteenth century when about 50 elements were discovered and scientists began to wonder if the elements vary from each other or if a pattern is represented in the arrangement of the elements. A number of scientists tried different kinds of patterns. For example‚ the German scientist Johann Wolfgang Döbereiner tried
Premium Atom Ancient Greece Greek mythology
or more elements are chemically combined. b) Chemical bonding involves either transferring or sharing electrons in the highest occupied energy levels (shells) of atoms in order to achieve the electronic structure of a noble gas. c) When atoms form chemical bonds by transferring electrons‚ they form ions. Atoms that lose electrons become positively charged ions. Atoms that gain electrons become negatively charged ions. Ions have the electronic structure of a noble gas (Group 0). d) The elements
Free Atom Electron Chemical bond
nucleus contains positively charged protons and uncharged neutrons. The electron cloud is composed of negatively charged electrons. Elements in the same row are similar in size. Elements in the same column have similar electronic and chemical properties. An s orbital has a sphere of electron density and is lower in energy than the other orbitals of the same shell. A p orbital has a dumbbell shape and contains a node of electron density at the nucleus. It is higher in energy than an s orbital.
Premium Atom Covalent bond Chemical bond
a molecule or ion‚ follow these steps: •Step 1: Count up the number of valence electrons for each atom‚ and total them up to give the total number of electrons for the molecule. If the molecule is an ion‚ include that charge in the count. For example‚ for a +1 ion‚ subtract one electron‚ and for a -2 ion add two electrons to the total count. (For more information about how to count the number of valence electrons per atom‚ see the related questions link to the left of this answer). •Step
Free Atom Chemical bond Electric charge
MANIPULATIONS: Cathode rays can be manipulated in a number of ways: 1) SPEED a. The speed the rays travel can be changed by changing the voltage between the anode and cathode. The voltage change changes the potential energy of the electrons. As it travels between the anode and the cathode‚ this energy is transformed into kinetic energy‚ therefore changing the speed of the particles. 2) NUMBER OF RAYS b. The number of cathode rays can be further manipulated by the introduction
Premium Electron Photon
Xxx.comTheories of light In the seventeenth century two rival theories of the nature of light were proposed‚ the wave theory and the corpuscular theory. The Dutch astronomer Huygens (1629-1695) proposed a wave theory of light. He believed that light was a longitudinal wave‚ and that this wave was propagated through a material called the ’aether’. Since light can pass through a vacuum and travels very fast Huygens had to propose some rather strange properties for the aether: for example; it must
Premium Chemical bond Atom Covalent bond
his discovery of electrons. He found the green beam produced by the cathode ray tube was a completely negatively charged material. Experimenting with different electrically charged plates and magnets in the cathode ray tube and observing the deflection of the rays he had enough evidence to say that particles smaller than atoms existed. By doing this experiment multiple times he compiled enough data to conclude that the mass of one of these particles‚ which he called an electron‚ was lighter than
Premium Electron Atom Neutron