Question

what is atom and atomic number or atomic mass and unit ​

Answer 1

Answer:

atoms are made up of three particles: protons, neutrons and electrons — which are composed of even smaller particles, such as quarks. Atoms were created after the Big Bang 13.7 billion years ago. ... Quarks came together to form protons and neutrons, and these particles combined into nuclei.

atomic mass number of protons and the number of neutrons determine an element's mass number: mass number = protons + neutrons.

atomic no is the number of protons in the nucleus of an atom, which is characteristic of a chemical element and determines its place in the periodic table.

Explanation:

hope that helps u :)

Answer 2

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ᴛʜᴇ ᴀᴛᴏᴍɪᴄ ᴍᴀss ᴏғ ᴀɴ ᴇʟᴇᴍᴇɴᴛ ɪs ᴛʜᴇ ᴀᴠᴇʀᴀɢᴇ ᴍᴀss ᴏғ ᴛʜᴇ ᴀᴛᴏᴍs ᴏғ ᴀɴ ᴇʟᴇᴍᴇɴᴛ ᴍᴇᴀsᴜʀᴇᴅ ɪɴ ᴀᴛᴏᴍɪᴄ ᴍᴀss ᴜɴɪᴛ (ᴀᴍᴜ, ᴀʟsᴏ ᴋɴᴏᴡɴ ᴀs ᴅᴀʟᴛᴏɴs, ᴅ). ᴛʜᴇ ᴀᴛᴏᴍɪᴄ ᴍᴀss ɪs ᴀ ᴡᴇɪɢʜᴛᴇᴅ ᴀᴠᴇʀᴀɢᴇ ᴏғ ᴀʟʟ ᴏғ ᴛʜᴇ ɪsᴏᴛᴏᴘᴇs ᴏғ ᴛʜᴀᴛ ᴇʟᴇᴍᴇɴᴛ, ɪɴ ᴡʜɪᴄʜ ᴛʜᴇ ᴍᴀss ᴏғ ᴇᴀᴄʜ ɪsᴏᴛᴏᴘᴇ ɪs ᴍᴜʟᴛɪᴘʟɪᴇᴅ ʙʏ ᴛʜᴇ ᴀʙᴜɴᴅᴀɴᴄᴇ ᴏғ ᴛʜᴀᴛ ᴘᴀʀᴛɪᴄᴜʟᴀʀ ɪsᴏᴛᴏᴘᴇ༄