COMPOSITION OF POLLUTION - FREE GROUND LEVEL AIR Nitrogen 78.08% Oxygen 20.95% Carbon Dioxide 0.03% COMPOSITION OF UNIVERSE COMPOSITION OF EARTH Hydrogen 60.40% Iron 35.4% Helium 36.56% Oxygen 27.8% Oxygen 0.96% Magnesium 17.0% Carbon 0.30% Silicon 12.6% ELEMENTS 90 Naturally occurring 19 Synthesized 109 TOTAL ATOM Chapter 3 What is it? Def: The smallest particle still having the characteristics of an element. It is made up of smaller particles: electrons, protons, and neutrons. Simplest atom is H (hydrogen). electron
How are Neutrons different between Protons? How are they similar? Neutrons are different to protons as Neutrons have no overall charge and Protons have a positive charge. They are similar because protons and neutrons are both situated in the nucleus which is the centre of the atom. Describe the differences between protons and electrons The difference between protons and electrons is that protons are positively charged and that elections are negatively charged.
Subatomic Particles and the periodic table 1. The three particles and their properties An atom has no overall charge. The protons (positively charged) and neutrons (no charge) make up the nucleus of an atom, and this is surrounded by negatively charged electrons. There are as many protons as electrons, so they balance each other out, creating a neutral relative charge on the atom. Neutrons, Protons and electrons are all sub-atomic particles.
Litmus test: Red turned blue and blue had no reaction Dilute HCl: Fizzes and substance turns yellowish while bubbling the back to white. Dilute NaOH: Dissolves and substance became a bit thick Substance: CuCO3 Color: Green Odor: Yes Effect of Heat: Turned into black powder Solub. or Reaction w/cold H2O: No reaction. Solub. or Reaction w/hot H2O: No reaction Litmus test: No change on blue or red.
Fluorine April 6th, 2011 Fluorine is the most reactive chemical element and the lightest member of the halogen elements. Fluorine is a nonmetal and is part of group 17 (group VIIa) of the periodic table. Its density is 0.001696 grams per cubic centimeter. Its chemical activity can be attributed to its extreme ability to attract and to the small size of its atoms. Fluorine is a corrosive pale yellow gas.
Helium is good for overhead, because it is lighter and thus flows upward. Argon allows easier arc starting and a smoother, more stable arc than helium does. Actually, argon pretty much is the most widely used shielding gas nowadays. TIG uses a tungsten electrode that is nonconsumable. In other words it does not burn up like an electrode in stick welding or the wire in metal inert gas (MIG) welding does.
A. II only B. III only C. II and III D. I only 6. A hydrate is a A. buffer solution of water B. compound in which hydrogen is combined with an element less electronegative than itself C. compound containing a definite number of water molecules in its chemical composition D. salt containing the hydroxyl radical 7. Two moles of hydrogen react with 1 mole of oxygen to produce which of the following? A. 1 mole of water B.
The atomic masses of two isotopes of cobalt are 59 and 60. a) What is the number of protons and neutrons in each? • The protons are the same otherwise it wouldn't be cobalt = 27 So the remainders are neutrons = 32 or 33 b) What is the number of orbiting electrons in each when the isotopes are electrically neutral? • Electrons = protons = 27, if electrically
Which type of intermolecular attraction (dispersion force, or hydrogen bond) exists in each of the following liquids? hydrogen bond hydrogen bond dispersion force hydrogen bond Predict which liquid in each pair has the higher boiling point. CH3COOH C2H5OH If the molecules in a liquid are weakly attracted, which of the following properties has a high value? vapor pressure (high when attraction is low) boiling point is low (it is only high when molecules are strongly attracted) viscosity is low (it is only high when molecules are strongly attracted) surface tension is low (it is only high when molecules are strongly attracted) Distinguish between a solid and a liquid at the molecular level. Solids and liquids differ at
It can also reacts with oxygen at high temperatures. Gadolinium has a hexagonal closely packed structure at ambient temperatures, but transforms at temperature of 1262 degree Celsius to a body centred cubic structure. This metal is paramagnetic at room temperature, but becomes ferromagnetic (strongly attracted by a magnet) when cooled below 20degrees Celsius and also shows the magnetoric effects ( meaning that when entering magnetic fields its temperature rises and its temperature decrease when exiting magnetic fields. Gadolinium has a greatest ability to capture thermal neutrons of all elements; and stable in dry air, but tarnishes off in moist environments forming gadolinium (III) oxide. It has a melting point of 1585K (which is the same as 1312°C 2394°F), heat of fusion of 10,05 kJ/mol, and boiling point of 3546 K( 3273 °C, 5923 °F).