Atomic Structure Chem test

A 100.00-gram sample of naturally occurring boron contains 19.78 grams of boron-10 (atomic mass = 10.01 atomic mass units) and 80.22 grams of boron-11 (atomic mass = 11.01 atomic mass units). Which numerical setup can be used to determine the atomic mass of naturally occurring boron?

1, (0.1978)(10.01) + (0.8022)(11.01)

What determines the order of placement of the elements on the modern Periodic Table?

1, Atomic number

Which statement identifies the element arsenic?

1, arsenic has an atomic number of 33

An atom is electrically neutral because the

1, number of protons equals to number of electrons

The mass of 12 protons is approximately equal to

2, 12 atomic mass units

The most common isotope of chromium has a mass number of 52. Which notation represent a different isotope of chromium?

2, 54/24Cr

What are the characteristics of a neutron?

2, it has no charge and a mass of 1 u.

Subatomic particles can usually pass undeflected through an atom because the volume of an atom Is composed of

2, largely empty space

An atom of potassium-37 and an atom of potassium-42 differ in their total number of

2, neutrons

Which statement describes the relative energy of the electrons in the shells of a calcium atom?

3, An electron in the third shell has more energy than an electron in the second shell

The atomic mass of an element is the weighted average of the masses of

3, all of its naturally occurring isotopes

A sample composed only of atoms having the same atomic number is classified as

3, an element

A student constructs a model for comparing the masses of subatomic particles. The student selects a small, metal sphere with a mass of 1 gram to represent an electron. A sphere with which mass would be most appropriate to represent a proton?

4, 2000 g

What is the structure of a krypton-85 atom?

4, 36 electrons, 36 protons, and 49 neutrons

According to the electron-cloud model of the atom, an orbital is a

4, Region of the most probable electron location

Which statement concerning elements is true?

4, all atoms of a given element must have the same atomic number