Calculations indicate that before this time temperatures were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled sufficiently that neutrons and protons could stick together. ...
Protons and Neutrons: What Are They?Jean Louis Van Belle
Elements in the same group have the same number of what? A. Protons B. Neutrons C. Electrons D. Valence E. lectrons 相关知识点: 试题来源: 解析 D。原因:“Elements in the same group have the same number of valence electrons.”。 反馈 收藏 ...
Visible matter, also called baryonic matter, consists of baryons — an overarching name for subatomic particles such asprotons, neutrons and electrons. Scientists only speculate what dark matter is made of. It could be composed of baryons but it could also be non-baryonic, which means consistin...
a毫无疑问 ) he is qualified for the job. Without a doubt) he is qualified for the job. [translate] aAn atom containing 34 protons, 43 neutrons, and 34 electrons would have what symbol? 包含34个氢核、43个中子和34个电子的原子将有什么标志? [translate] ...
well, unfortunately not. science has known for a long time that atoms mainly consist of empty space with electrons spinning around a central nucleus of protons and neutrons. and science has known for somewhat less time that these particles, which were once thought to be fundamental, are ...
What are the parts of an atom?Most atoms have three different subatomic particles inside them: protons, neutrons, and electrons. The protons and neutrons are packed together into the center of the atom (which is called the nucleus) and the electrons, which are very much smaller, whizz around...
The atomic mass is the mass of an atom. Although the SI unit of mass is the kilogram, the atomic mass is often expressed in the non SI-unit dalton, where one dalton is defined 1/12 of the mass of a single carbon-12 atom, at rest. The protons a...
Protons have arelative massof 1, which is the same as the relative mass of neutrons. Thenumber of protons in an atomis called the 'Atomic Number' of that atom and is sometimes referred to as 'Z'. This is important because itdefines the type of atom, i.e. whichelementit is an atom...
What will an atom do if it has 1 to 3 valence electrons? An atom of an element has 10 protons. what is also true of that atom? A single atom of an element has 11 protons, 11 electrons, and 12 neutrons. Which element is it? What has 8 protons and 10 electrons? What is the ion...