Chemistry 1150 Chapter 2

What charge do ions formed from elements in group 5A such as nitrogen(N) and arsenic(As) have?

-3

Calculate the number of moles represented by 21.7 g iron (Fe).

0.389 mol of Fe

How many atoms are the in 5.0 g of Mg?

1.2 x10^23 atoms of Mg

How many atoms are in a 10.0 g sample of molybdenum (Mo)?

10.0 g of Mo x 1 mold of Mo/ 95.94 of Mo x 0.104 moles of Mo

How many neutrons does magnesium- 26 have?

14 Neutrons

Calculate the mass, in grams, of 15.2 mol of boron.

15.2 mol of B x 10.811 g of B / 1 mol of B = 164 g of B

What is the molar mass for potassium rounded to four significant figures?

39.10 g/mol of K

What is the numerical value for Avogadro's number?

6.022x10^23

The density of lithium is 0.546 g/cm3. What volume is occupied by 3.66 ´ 1023 atoms of lithium?

7.73 cm^3 of Li

How many neutrons are in an atom of selenium (Se) with a mass number of 79?

79-34 = 45 Neutrons

How many moles of atoms are in 9.23 x 10 ^25 atom of sulfur?

9.23 x 10^25 atoms S x 1 mol S/6.022x10^23 atom S = 153 moles of S

What is a mole? (Provide 2 statements)

A counting unit, like a dozen but instead of 12 particles in a dozen, there are 6.022 x10^23 particles in a mole

From the results of his gold foil experiment, Ernest Rutherford concluded that

Atoms are composed of a small, dense nucleus surrounded by a cloud of electrons

What charges are commonly observed for beryllium and oxygen, respectively, when they form compounds?

Be: +2, O: -2

Which element can be classified as a transition metal?

Cobalt

Calculate the number of moles represented by 21.7 g iron (Fe).

Lithium

In the periodic table, the number below the elemental symbol is the

Molar Mass

The atomic number is defined as

The number of protons in the nucleus of an atom

What is the mass number defined as:

The numberof protons plus the number of neutrons in the nuceaus of an atom

Copper has two naturally occurring isotopes. A typical sample consists of 69.17% (62.939598 amu) and 30.83% (64.927793 amu). Calculate the average atomic mass of copper.

[(69.01%)*(62.939598 amu)] + [(30.83%)*(64.927793 amu)]/ 100% = 63.45 amu of Cu

An element containing 26 protons, 26 electrons and 30 neutrons will have the symbol:

^56 Fe

Lithium has two stable isotopes 6Li and 7Li with masses of 6.017 amu and 7.018 amu respectively. Which is the more abundant of the two?

^7 Li

Carbon can exist in two distinct and different forms, graphite and diamond. These forms are called_____

allotropes