Alpha particles. Alpha particles are made of 2 protons and 2 neutrons. This means that they have a charge of +2, and a mass of 4. (the mass is measured in atomic mass units, where each proton & neutron=1) We can write them as , or, because they're the same as a helium nucleus, . Alpha particles are relatively slow and heavy.
For more, visit TIME Health. 1  The average attention span for the notoriously ill-focused goldfish is nine seconds, but according to a new study from Microsoft Corp., people now generally lose concentration after eight seconds, highlighting the affects of an increasingly digitalized lifestyle on the brain.
A 4-year-old child's attention span is about 15 minutes according to child development experts. Therefore, 15 minutes is a reasonable duration for Circle Time at preschool (25-30 minutes is reasonable for kindergarten). However, it's common for teachers to conduct Circle Times that go on for 45 minutes to an hour.