Group VII Elements - Halogens The Group VII elements are called HALOGENS. The name Halogen means
"salt - former" and is based on the fact that the elements combine
with most metals to form salts. (halides)
ELEMENT
=======
FLUORINE
========
CHLORINE
BROMINE
=======
IODINE
======
State at 20oC
GAS
---
GAS
---
LIQUID
------
SOLID
-----
Colour
PALE YELLOW
PALE GREEN
RED-BROWN
BLACK
Melting Point
(0C)
- 220
- 101
- 7
113
Boiling Point
(0C)
- 188
- 35
59
183
ELECTRON AFFINITY
Electron affinity is the enthalpy change when gaseous atoms of an
element gain electrons to become negative ions.
The FIRST ELECTRON AFFINITY of an element is the ENTHALPY CHANGE WHEN
ONE MOLE OF GASEOUS ATOMS GAINS ELECTRONS TO FORM ONE MOLE OF GASEOUS
IONS.
Electron affinity DECREASES as you DESCEND the group VII:
F à 333kJ
Cl à 346kJ of energy is released for every one mole of F/Cl/Br/I
Br à 324kJ atoms changing to a mole of F/Cl/Br/I ions.
I à 295kJ
This trend can be explained by the fact that as you descend the group,
the X- ion becomes less stable and is therefore less likely to form. H
is less stable because electrons are less strongly attracted due to
the fact that the valence electrons are further from the attractive
Neon was discovered in 1898 by British chemists Sir William Ramsay and Morris W. Travers as a component of the most volatile fraction of liquefied crude argon obtained from air. Upon applying an electric current to it, the chemists found that it had an orange glow, and they decided that it was not argon, but rather a new element altogether.
In Chemistry, Neodymium is one of the 118 elements found on Mendeleev’s Periodic Table. An element is a substance that is made entirely from one type of atom and is then advantageously placed in the periodic table which categorizes all elements of the universe. Neodymium was discovered to have a “twin element” and is used for anything from high-powered fans to cellular phones.
Strontium was discovered by Adair Crawford, an Irish chemist, in 1790 while studying the mineral witherite (BaCO3). When he mixed witherite with hydrochloric acid (HCl), he did not get the results he expected. He assumed that his sample of witherite was contaminated with an unknown mineral, a mineral he named strontianite (SrCO3). Strontium was first isolated by Sir Humphry Davy, an English chemist, in 1808 through the electrolysis of a mixture of strontium chloride (SrCl2) and mercuric oxide (HgO). Strontium reacts vigorously with water and quickly tarnishes in air, so it must be stored out of contact with air and water. Due to its extreme reactivity to air, this element always naturally occurs combined with other elements and compounds. Strontium is very
For example, what are the names of Fe2O3 and FeO. Iron oxide is not an adequate answer; it fails to distinguish between the two possible oxidation states of iron. Is it iron (II) or iron (III). To decide, you must know use the combination of the oxide's fixed oxidation state of 2- with iron's oxidation state required to total for a compound charge of zero. The compound iron(II) oxide, FeO, iron had the oxidation state of 2+ which balances the charge of the oxide ion which is 2-. For the compound iron(III) oxide, Fe2O3, the roman numeral placed after the name of the metal clearly states the charge of each iron atom as 3+. The older system of naming applies either the suffixes —ic for the ion of higher charge and —ous for the ion of lower charge; thus Fe3+ ion can be referred to as ferric and Fe2+ ion as ferrous.
Beryllium has the symbol Be. In the older chemical literature, beryllium is called glucinium after the Greek word glykys meaning sweet, because of Vauquelin's initial description and observation of Beryllium. Beryllium's atomic number is 4, its atomic weight is 9.01 and in its pure metal form it melts at 1278 degrees Celsius.
Oxides of Hydrogen Introduction: Hydrogen atoms can react with oxygen atoms forming different compounds. There are mainly two types, one is water and the other is hydrogen peroxide. Structure: A water molecule is made up of two hydrogen atoms and one oxygen atom joining together by covalent bonds. The shape of it is bent and its bond angle is of 105°. The structure is shown below.
Elements are the basic building blocks of matter due to the fact that they are chemically the simplest substances. Whether we can find them in the air or in our gold/silver necklaces, elements are everywhere! One essential element is hydrogen, the first element on the period table (located under Group 1 as an alkaline metal) is composed of a single proton and electron; therefore having an atomic number and atomic mass of 1 and electron configuration of 1s1. In fact, hydrogen is the lightest, simplest and most commonly found chemical element in the universe (it makes up about 90% of the universe by weight). Interestingly enough, the heavier elements on the periodic table were either made from hydrogen or other elements that were made from hydrogen. The most common isotope formed of hydrogen is protium, with 1 proton and no neutrons. Hydrogen can also exist as both positively or negatively charged. The physical form of hydrogen at room temperature is a colorless and odorless gas. Hydrogen gas is extremely flammable and because of this chemical property, it is used as fuel for the main engine of space shuttles. Hydrogen is an important element and has received a lot of recognition throughout history for its usefulness.
One of nature's greatest possessions, is life, and every part of life depends on molecules. Four common molecules are Carbohydrates, Proteins, Lipids and Nucleic Acids. Within these molecules contains part, or all, of the four major elements, Carbon, Hydrogen, Oxygen, and Nitrogen, (C.H.O.N). It is an essential part of life to have these molecules or their would be no living creatures. Molecules, Atoms, and elements are all apart of the body and every creature needs them.
These complex metal hydrides have high gravimetric storage capacity than the simple metal hydrides. Nitrogen containing hydrides such as amines or imides, and boron containing hydrides (borohydrides) are the main categories in complex metal hydrides. Lithium imide (Li2NH), magnesium amide (Mg(NH2)2), lithium borohydride (LiBH4) and sodium borohydride (NaBH4) are the actively explored complex metal hydrides for the hydrogen storage applications. Li2NH reversibly store 6.5 wt% of hydrogen however the required temperature to burn the fuel is high and cannot be used in onboard vehicles. In addition, amides and imides produce ammonia as the effluent. The LiBH4 and NaBH4 have a very high gravimetric storage capacity of up to 18 wt%. However, desorption temperature of 673 K is required to remove the hydrogen atoms. Thus these complex metal hydrides are not promising materials for hydrogen storage (Satyapal et al (2007 & Durbin & Malardier-Jugroot
Vecuronium-bromide is a drug used prior to and during surgery. It has several benefits in surgical situations which makes it an ideal drug. It has a rapid onset and recovery time, it is easily administered which is a benefit for maintenance doses, it paralyses the trachea which aids in ease of endotracheal tubation, it also has very little cardiovascular or histamine releasing effects. All of these things combined make it an ideal drug in conjunction with other anesthesia medications for surgery as well as in long term use of intensive care unit patients (DailyMed 2009.)
Heavy metal music has developed greatly ever since it was created in the late 1960’s, evolving into large and varied categories of subgenres. It is not uncommon for types of metal to be confused for one another despite their distinct differences. There are hundreds of subgenres, but three of them will be discussed, the bluesy and distorted doom metal, the fast and fantastical power metal, and the ill reputed black metal.
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Mention 2 elements that can be isolated from the pitchblende and one uses of any of them?
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• The use of a catalyst will speed up the reaction as long as the catalysts electrode potentials are feasible for each step in the reaction. Since a catalyst lowers the activation energy and takes the reaction through a different route, according to the Maxwell-Boltzmann diagram, at a constant temperature more particles are able to react as demonstrated by the diagrams below: