HAPPY HALLOWEEN

CHEMISTRY - DANGER MODULE #11

Dangerous Particles

Radioactivity occurs when an atomic nucleus breaks down into smaller particles. There are three types of particles: alpha, beta, and gamma. Alpha particles are positively charged, beta particles are negatively charged, and gamma particles have no charge. The particles also have increasing levels of energy. Alpha has the lowest energy, beta has a bit more, and then gamma is the fastest and most energetic of all the emission particles. 

The term half-life describes the time it takes for the amount of radioactivity to go down by one-half. Let's say you have some uranium (U) (don't try this at home!) and it's radioactive. When your measurements tell you that the level of radioactivity has gone down by one-half, the amount of time that has passed is the half-life. Every isotope has its own unique half-life. The half-life of uranium-235 is 713,000,000 years. The half-life of uranium-238 is 4,500,000,000 years. That's a long time to wait for the radioactivity to decrease. 

Harnessing the Energy

Nuclear energy is the energy released when the nuclei (nuclei is the plural of nucleus) of atoms split or are fused. You know the nucleus is made up of protons and neutrons. Nuclear forces hold all of the pieces together. Fusion is when two nuclei come together. Fission is when one nucleus is split into two or more parts. Huge amounts of energy are released when either of these reactions occurs. Fusion reactions create much of the energy given off by the Sun. Fission creates the much smaller particles that make up the protons and neutrons that physicists are studying every day. In our nuclear reactors, fission is the main process. In the Sun, fusion is the big process. 

Atoms from the Mirror Universe

Since we're talking a little bit about atomic and nuclear physics, we wanted to tell you about antimatter. It's not just found in television shows. Scientists have proved that it is real. While a regular atom has positive and neutral pieces (protons/neutrons) in the nucleus and negative pieces in orbiting clouds (electrons), antimatter is just the opposite. Antimatter has a nucleus with a negative charge and little positive pieces in the orbits. Those positively charged pieces are called positrons. According to news reports in 2010, scientists at CERN (a particle collider) created antihydrogen atoms. They couldn't really do anything with them, since they lasted for less than a second... but they made them! 

CHEMISTRY - ELEMENT OF THE DAY - SULFUR

16

S

Sulfur

32.065

Atomic Number: 16

Atomic Weight: 32.065

Phase at Room Temperature: Solid

Element Classification: Non-metal

Period Number: 3    Group Number: 16   

Group Name: Chalcogen

What's in a name? From the Sanskrit word sulvere and the Latin word sulphurium.

Say what? Sulfur is pronounced as SUL-fer.

History and Uses:

Sulfur, the tenth most abundant element in the universe, has been known since ancient times. Sometime around 1777, Antoine Lavoisier convinced the rest of the scientific community that sulfur was an element. Sulfur is a component of many common minerals, such as galena (PbS), gypsum (CaSO₄·2(H₂O), pyrite (FeS₂), sphalerite (ZnS or FeS), cinnabar (HgS), stibnite (Sb₂S₃), epsomite (MgSO₄·7(H₂O)), celestite (SrSO₄) and barite (BaSO₄). Nearly 25% of the sulfur produced today is recovered from petroleum refining operations and as a byproduct of extracting other materials from sulfur containing ores. The majority of the sulfur produced today is obtained from underground deposits, usually found in conjunction with salt deposits, with a process known as the Frasch process.

Sulfur is a pale yellow, odorless and brittle material. It displays three allotropic forms: orthorhombic, monoclinic and amorphous. The orthorhombic form is the most stable form of sulfur. Monoclinic sulfur exists between the temperatures of 96°C and 119°C and reverts back to the orthorhombic form when cooled. Amorphous sulfur is formed when molten sulfur is quickly cooled. Amorphous sulfur is soft and elastic and eventually reverts back to the orthorhombic form.

Most of the sulfur that is produced is used in the manufacture of sulfuric acid (H₂SO₄). Large amounts of sulfuric acid, nearly 40 million tons, are used each year to make fertilizers, lead-acid batteries, and in many industrial processes. Smaller amounts of sulfur are used to vulcanize natural rubbers, as an insecticide (the Greek poet Homer mentioned "pest-averting sulphur" nearly 2,800 years ago!), in the manufacture of gunpowder and as a dying agent.

In addition to sulfuric acid, sulfur forms other interesting compounds. Hydrogen sulfide (H₂S) is a gas that smells like rotten eggs. Sulfur dioxide (SO₂), formed by burning sulfur in air, is used as a bleaching agent, solvent, disinfectant and as a refrigerant. When combined with water (H₂O), sulfur dioxide forms sulfurous acid (H₂SO₃), a weak acid that is a major component of acid rain.