248 Cm has been produced only in milligram amounts. Curium is similar in some regards to gadolinium, its rare earth homolog, but it has a more complex crystal structure. Curium metal is lustrous, malleable, silver in color, chemically reactive, and is more electropositive than aluminum. Curium metal exist in two crystal forms, a double hexagonal close packed (dhcp) and a high temperature face-centered cubic close packed (fcc) structure. Metallic curium dissolves rapidly in dilute acid to form Cm(III) solutions. Curium metal surfaces rapidly oxidize in air to form a thin film possibly starting out as CmO, Oxidation then progressing to Cm 2 O 3, and eventually to form stable CmO 2. Note however that the formation of divalent compounds of curium such as CmO have never been observed in bulk form.
Video: Read-Only Memory (ROM): Definition & Types. Computers have various types of memory. Read-only memory (ROM) contains the instructions for what needs to happen when a computer is powered on. The data in ROM cannot be modified, or only with great difficulty, since these instructions do not need to be changed very often.
Random-access memory (RAM /rÃ¦m/) is a form of computer data storage. A random-access memory device allows data items to be read or written in almost the same amount of time irrespective of the physical location of data inside the memory.