21 Plutonium Facts (Pu or Atomic Number 94)

21 Plutonium Facts (Pu or Atomic Number 94) You probably know that plutonium is an element and that plutonium is radioactive, but what else do you know about it? Learn more with these fascinating facts about plutonium. Fast Facts: Plutonium Name: PlutoniumElement Symbol: PuAtomic Number: 94Atomic Mass: 244 (for the most stable isotope)Appearance: A silvery-white solid metal at room temperature, which quickly oxidizes to dark gray in airElement Type: ActinideElectron Configuration:  [Rn] 5f6  7s2 Facts About Plutonium Here are 21 useful and interesting facts about plutonium: The element symbol for plutonium is Pu, rather than Pl, because this was a more amusing, easily remembered symbol.  The element was synthetically produced by Glenn T. Seaborg, Edwin M. McMillan, J.W. Kennedy, and A.C. Wahl at the University of California at Berkeley in 1940–1941. The researchers submitted news of the discovery and the proposed name and symbol to the journal Physical Review but withdrew it when it became apparent plutonium could be used for an atomic bomb. The elements discovery was kept secret until after World War II.Pure plutonium is a silvery-white metal, although it quickly oxidizes in air to a dull finish.The atomic number of plutonium is 94, meaning all atoms of plutonium have 94 protons.  It has an atomic weight around 244, a melting point of  640 C (1183 F), and a boiling point of  3228 C (5842 F).Plutonium oxide forms on the surface of plutonium exposed to air. The oxide is pyrophoric, so pieces of plutonium might glow like embers as the outer coating burns. Plutonium is one of a handful of radioactive elements that glows in the dark, although the glow is from heat. Ordinarily, there are six allotropes, or forms, of plutonium. A seventh allotrope exists at high temperatures. These allotropes have different crystal structures and densities. Changes in environmental conditions readily cause plutonium to shift from one allotrope to another, making plutonium a difficult metal to machine. Alloying the element with other metals (e.g., aluminum, cerium, gallium) helps make it possible to work and weld the material.Plutonium displays colorful oxidation states in aqueous solution. These states tend not to be stable, so plutonium solutions may spontaneously change oxidation states and colors.  The colors of the oxidation states are as follows:Pu(III) is lavender or violet.​Pu(IV) is golden brown.Pu(V) is pale pink.Pu(VI) is orange-pink.Pu(VII) is green. Note this oxidation state is uncommon. The 2 oxidation state also occurs in complexes.Unlike most substances, plutonium increases in density as it melts. The increase in density is about 2.5%. Nea r its melting point, liquid plutonium also exhibits higher-than-usual viscosity and surface tension for a metal. Plutonium is used in radioisotope thermoelectric generators, which are used to power spacecraft. The element has been used in nuclear weapons, including the Trinity test and the bomb that was dropped on Nagasaki. Plutonium-238 was once used to power heart pacemakers.Plutonium and its compounds are toxic and accumulate in bone marrow. Inhalation of plutonium and its compounds increases the risk of lung cancer, although many people have inhaled substantial amounts of plutonium yet didnt develop lung cancer. Inhaled plutonium is said to have a metallic taste.Criticality accidents involving plutonium have occurred. The amount of plutonium required for critical mass is about one-third that necessary for uranium-235. Plutonium in solution is more likely to form critical mass than solid plutonium because the hydrogen in water acts as a moderator.Plutonium is not magnetic. Other members of the element group stick to magnets, but plutonium can have a variable number of electrons in its valenc e shell, which makes it difficult for the unpaired electrons to align in a magnetic field. The element name follows the trend of uranium and neptunium being named for planets outward from the Sun. Plutonium is named for the dwarf planet Pluto.Plutonium is not a good conductor of electricity or heat, unlike some metals.The alpha form of plutonium is hard and brittle, while the delta form is soft and ductile.Plutonium occurs naturally in the Earths crust in uranium ores, but it is very rare. The main source of the element is synthesis in reactors from uranium-238.Plutonium is a member of the actinide element group, which makes it a type of transition metal.

Description and Examples of Variables

Description and Examples of Variables A variable is a name for a place in the computers memory where you store some data. Imagine a very large warehouse with lots of storage bays, tables, shelves, special rooms etc. These are all places where you can store something. Lets imagine we have a crate of beer in the warehouse. Where exactly is it located? We wouldnt say that it is stored 31 2 from the west wall and 27 8 from the north wall. In programming terms we also wouldnt say that my total salary paid this year is stored in four bytes starting at location 123,476,542,732 in RAM. Data in a PC The computer will place variables in different locations each time our program is run. However, our program knows exactly where the data is located. We do this by creating a variable to refer to it and then let the compiler handle all the messy details about where it is actually located. It is far more important to us to know what type of data we will be storing in the location. In our warehouse, our crate might be in section 5 of shelf 3 in the drinks area. In the PC, the program will know exactly where its variables are located. Variables Are Temporary They exist just as long as they are needed and are then disposed of. Another analogy is that variables are like numbers in a calculator. As soon as you hit the clear or power off buttons, the display numbers are lost. How Big Is a Variable As big as is needed and no more. The smallest a variable can be is one bit and the largest is millions of bytes. Current processors handle data in chunks of 4 or 8 bytes at a time (32 and 64 bit CPUs), so the bigger the variable, the longer it will take to read or write it. The size of the variable depends on its type. What Is a Variable Type? In modern programming languages, variables are declared to be of a type. Apart from numbers, the CPU does not make any kind of distinction between the data in its memory. It treats it as a collection of bytes. Modern CPUs (apart from those in mobile phones) can usually handle both integer and floating point arithmetic in hardware. The compiler has to generate different machine code instructions for each type, so knowing what the type of variable helps it generate optimal code. What Types of Data Can a Variable Hold? The fundamental types are these four. Integers (both signed and unsigned) 1,2,4 or 8 bytes in size. Usually referred to as ints.Floating Point Numbers up to 8 bytes in size.Bytes. These are organized in 4s or 8s (32 or 64 bits) and read in and out of the CPUs registers.Text strings, up to billions of bytes in size. CPUs have special instructions for searching through large blocks of bytes in memory. This is very handy for text operations. There is also a general variable type, often used in scripting languages. Variant - This can hold any type but is slower to use. Example of Data Types Arrays of types- single dimension like drawers in a cabinet, two-dimensional like post office sorting boxes or three dimensional like a pile of beer crates. There can be any number of dimensions, up to the limits of the compiler.Enums which are a restricted subset of integers.  Read about  what is an enum is.Structs are a composite variable where several variables are lumped together in one big variable.Streams provide a way to manage files. Theyre a form of a string.Objects, are like structs but with much more sophisticated data handling. Where are Variables Stored? In memory but in different ways, depending on how they are used. Globally. All parts of the program can access and change the value. This is how older languages like Basic and Fortran used to handle data and it is not considered a good thing. Modern languages tend to discourage global storage though it is still possible.On the Heap. This is the name for the main area used. In C and C, access to this is via pointer variables.On the Stack. The stack is a block of memory that is used to store parameters passed into functions, and variables that exist local to functions. Conclusion Variables are essential to procedural programming, but it is important not to get too hung up on the underlying implementation unless you are doing systems programming or writing applications that have to run in a small amount of RAM. Our rules regarding variables: Unless you are tight on ram or have large arrays, stick with ints rather than a byte (8 bits) or short int (16 bits). Especially on 32 Bit CPUs, there is an extra delay penalty in accessing less than 32 bits.Use floats instead of doubles unless you need the precision.Avoid variants unless really necessary. They are slower.