Chemistry
From the symbol 42He for the element helium, write down the mass number and the atomic number of the element.
Related Questions
The element X has the electronic configuration 2, 8, 18, 8, 1. Without identifying X,
(a) predict the sign and charge on a simple ion of X.
(b) write if X will be an oxidising agent or a reducing agent and why.
Define the terms :
(a) mass number
(b) ion
(c) cation
(d) anion
(e) element
(f) orbit.
An atom of an element has two electrons in the M shell. What is the
(a) atomic number
(b) number of protons in this element?
Five atoms are labelled A to E.
Atoms Mass no. Atomic no. A 40 20 B 19 9 C 7 3 D 16 8 E 14 7 (a) Which one of these atoms:
(i) contains 7 protons
(ii) has electronic configuration 2, 7?
(b) Write down the formula of the compound formed between C and D.
(c) Predict :
(i) metals
(ii) non-metals.