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.
The 2 types of computer memory are ROM and RAM. These stand for Read Only Memory and Random Access Memory, respectively. Read Only memory is the type of memory that is non-volatile, which means that the data contained here is never lost, even when the computer is shut down.