Answer:
Explanation:
Metal elements form positively charged ions called cations because they are located on the left side of the periodic table These elements all have valence electrons in an s orbital. These electrons are relatively easy for the atom to lose to achieve a stable octet of electrons in its outermost energy shell.
There are types of lens; concave and convex lens.
The concave lens is a lens which has an inward curve in the middle, that is, the edges of the curve are thicker than the center of the lens, because of this, any light that enter the lens will spread out [diverge]. An image will look smaller and upright when viewed by a concave lens. Image formed by concave lens are usually VIRTUAL.
A concave lens will produce a real image ONLY if the object is located beyond the focal point of the lens.
A convex lens is a converging lens, this is because, the center of the lens is thicker than its edges. Any ray of light that passes through the lens will converge at the middle of the lens at point called principal focus. A convex lens produce a VIRTUAL image when the object is placed infront of the focal point. The virtual image formed is always magnified and upright.<span />
<span>A chemist adds 155.0ml of a 4.10 X 10^-5 mmol/L of a zinc oxalate (ZnC2O4)solution to a reaction flask. Calculate the mass in micrograms of zinc oxalate the chemist has added to the flask.
1mmol = 10^-3 mol
Therefore 4.10*10^-5mmol = 4.10*10^-8mol
molar mass ZnC2O4 = 65.39+(2*12.011)+(4*15.99) = 153.372g/mol
You have 4.10*10^-8 mol/litre =153.372 * 4.10*10^-8 = 6.29*10^-6 grams / litre (* see below)
But you have 155ml. Mass of ZnC2O4 = 155/1000*6.29*10^-6 g
Mass is = 9.75*10^-7 grams
1µg = 10^-6 g
You then have 9.75*10^-7/10^-6 = 0.975µg ZnC2O4
(*see below) at this point you could have said:
1µg = 10^-6 g therefore you have a solution of 6.29µg per litre,
155ml = 6.29*155/1000 = 0.975µg ZnC2O4</span>
NaCl or sodium chloride is composed of two metals: the cation is Na + while the anion is the Cl-. In this case, when two metals form a bond, valence electrons are transferred. NaCl is an ionic compound. In 2, upon chemical change, the properties of the compound resulting from the reaction are somewhat closely related from the elemental properties.
Answer:
See explanation
Explanation:
We can describe electrons using four sets of quantum numbers;
principal quantum number (n)
orbital quantum number (l)
magnetic quantum number (ml)
spin quantum number (ms)
Since no two electrons in an atom can have the same value for all four quantum numbers according to Pauli exclusion theory, for the orbitals given one possible value for each quantum number is shown below;
For 1s-
n = 1, l= 0, ml = 0, ms= 1/2
For 2s-
n= 2, l =0, ml=0, ms=1/2
For 1s and 2s orbitals, there is only one possible value for ml which is zero.
