General Chemistry Chapter 2

What is the mass number of a chromium atom with 28 neutrons?

28 neutrons + 24 protons = 52

the understood sig fig amount for periodic table masses is?

4 sig figs

Group 2A: Alkaline Earth Metals

6 of them, Be, Mg, Ca, Sr, Ba, Ra all of these metals form ions with a +2 charge in compounds

Group 1A: Alkali Metals

6 of them, Li, Na, K, Rb, Cs, Fr, (not hydrogen) alkali metals form ions with a +1 charge in compounds

avagodros #

6.022x10^23 1 mole of atoms = 6.022 x10^23 atoms

How many neutrons are in atom of nickel with a mass number of 60?

60 - 28 protons = 32 nuetrons

Copper has two naturally occurring isotopes. A typical sample consists of 69.17% (62.939598 amu) and 30.83% (64.927793 amu). Calculate the atomic mass of copper. a) 62.93 amu b) 62.33 amu c) 62.45 amu d) 63.55 amu e) 63.93 amu

d

How many neutrons are in copper-63? a) 18 b) 24 c) 29 d) 34 e) 63

d

how to know which isotope is more abundant than another ?

mass # needs to be closest to the one on the periodic table

share characteristics of both metals and nonmetals

metalloids

1 mole copper atoms = 63.55 g of copper atoms OR 1 mol Cu = 63.55 g This quantity is also known as the

molar mass (an older term is atomic weight) Molar mass = MM = 63.55 g / mole (for copper)

do not conduct heat and electricity not ductile or malleable

nonmetals

nucleus( the tiny heart of the atom) is composed of ____________________ and _________, each having a mass of around 1 amu. The nucleus is surrounded by ___________ which have negligible mass, but do have an electrical charge of -1

protons (+1) and neutrons electrons

groups on the periodic table are

the vertical columns of elements they have similar chemical and physical properties

protons and electrons =

atomic number; ex Na atomic number 11 so there are 11 protons/electrons

1) From the results of his gold foil experiment, Ernest Rutherford concluded that a) electrons have a charge of +1.602 ´10-19C. b) atoms contain exactly equal numbers of neutrons and protons. c) atoms are composed of a small, dense nucleus surrounded by a cloud of electrons.

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

Law of Conservation of Matter

atoms are not created or destroyed during a reaction, only rearranged total mass of reactants = total mass of products

Group 3A most important thing

+3 charge

group 5A group 6A 7A

-3 -2 -1

1 amu =

1 amu = 1.661 x 10-24g.

2 statements to describe a mole ?

1) a counting unit like a dozen 2) 1 mole of particles is equal to 6.022x10^23 particles

Use the molar mass (MM) to convert from:

1) mass to moles 2) moles to mass

Use Avogadro's number (NA) to convert from:

1) number of atoms to moles 2) moles to number of atoms

allotrope

Different forms of the same element like graphite and diamond

an alternate name for the periodic chart, which is?

The Gram-Mole Chart The name is justified because underneath the symbol for each element is the number of grams that one mole of atoms of the element weighs. For example, one mole of copper atoms has a mass of 63.55 grams

All of the following statements are true EXCEPT a) for any neutral element, the number of protons and electrons are equal. b) isotopes of an element have the same atomic number. c) the mass number is the sum of the number of protons and neutrons. d) the atomic number equals the number of protons. all atoms of a given element have the same mass number.

a) all atoms of a given element have the same mass number.

Which of the following atoms contains the largest number of neutrons? a)31,15 P b)28,14 Si c)32,16 S d)36,16 S e)35,17 Cl

d)36,16 S

periods on the periodic table are

each horizontal row of elements

Protons Electrons Neutrons what is their electric charge and mass?

electrical charge Mass (amu) Positive (+1) 1.007 negative (-1) 0.0005 no electrical charge 1.009

element equals which letter mass number equals which letter

element (Z) mass #(A)

. Isotopes are types of atoms of the same _________but different _________

element (same Z) mass number (A)

law of chemical periodicity

element properties are periodic functions of their atomic numbers

The measurement unit for molar mass is

g/mol

We can also refer to the types of atoms in an element as ___________ of that element.

isotopes

to find neutrons you do what?

mass # - atomic number