Chemistry Atom Unit

Write the electron configuration for chromium

1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^4

Which concept in Dalton's atomic theory has been modified?

Atoms cannot be divided.

Ernest Rutherford

Conducted the famous gold-foil experiment and as a result concluded that 1) most of the atom was empty space 2) the positive charge is located in a dense nucleus. Therefore, he is credited with the discovery of the nucleus.

Who discovered the electron?

JJ Thomson

List the number of protons, neutrons, and electrons in C. 13, 6

Protons= 6 Neutrons= 7 Electrons= 6

who discovered the proton

Rutherford & Mosley

Who was the man who lived from 460 B.C.-370 B.C. and was among the first to suggest the idea of atoms

democritus

the sum of the protons and neutrons in an atom equals the

mass number

In what way are two isotopes of the same element different? Explain why isotopes of the same element have the same chemical behavior.

They have different number of neutrons so therefore have different mass numbers

Which of the following statements is true? a. Atoms of the same element may have different masses. b. Atoms may be divided in ordinary chemical reactions. c. Atoms can never combine with any other atoms. d. Matter is composed of large particles called atoms.

a. Atoms of the same element may have different masses.

How many protons, electrons, and neutrons does an atom with atomic number 50 and mass number 125 contain? a. 50 protons, 50 electrons, 75 neutrons c. 120 neutrons, 50 protons, 75 electrons b. 75 electrons, 50 protons, 50 neutrons d. 70 neutrons, 75 protons, 50 electrons

a: 50 protons, 50 electrons, 75 neutrons

What is the maximum number of orbitals in the p sublevel? a. 2 c. 4 b. 3 d. 5

b

What is the shape of the 3p atomic orbital? a. sphere c. bar b. dumbbell d. two perpendicular dumbbells

b: dumbbell

All atoms of the same element have the same ____. a. number of neutrons c. mass numbers b. number of protons d. mass

b: number of protons

The atomic number of an element is the total number of which particles in the nucleus? a. neutrons c. electrons b. protons d. protons and electrons

b: protons

Dalton's atomic theory included which idea? a. All atoms of all elements are the same size. b. Atoms of different elements always combine in one-to-one ratios. c. Atoms of the same element are always identical. d. Individual atoms can be seen with a microscope.

c: atoms of the same element are always identical

a subatomic particle with no charge

neutron

the central part of an atom, containing protons and neutrons

nucleus

a positively charged subatomic particle

proton

the average atomic mass of an element depends upon the

the mass and relative abundance of each isotope of that element

Isotopes of each element differ in

the number of neutrons in the nucleus.

Use the periodic table to determine the number of protons in an atom of barium.

56

Explain how the atoms of one element differ from those of another element.

Atoms differ because they have different amount of protons

What observations by Rutherford led to the hypothesis that atoms are mostly empty space, and that almost all of the mass of the atom is contained in an atomic nucleus?

He found that most particles went straight through but not all went through

plum pudding model

J.J Thomsons model of an atom, in which he thought electrons were randomly distributed within a positively charged cloud Model of the atom proposed by J.J Thomson as a result of his work with cathode ray tubes. In it, the neutral atom contains negatively charged particles (electrons) scattered throughout a lump of positive charge like raisins in plum pudding.

Who discovered the neutron?

James Chadwick

The smallest particle of an element that retains the properties of that element is a(n) ____. a. atom c. proton b. electron d. Neutron

a: atom

the smallest particle of an element that retains the properties of that element

atom

All atoms are ____. a. positively charged, with the number of protons exceeding the number of electrons b. negatively charged, with the number of electrons exceeding the number of protons c. neutral, with the number of protons equaling the number of electrons d. neutral, with the number of protons equaling the number of electrons, which is equal to the number of neutrons

c: Neutral, with the number of protons equaling the number of electrons

The principal quantum number indicates what property of an electron? a. position c. energy level b. speed d. electron cloud shape

c: energy level

The particles that are found in the nucleus of an atom are ____. a. neutrons and electrons c. protons and neutrons b. electrons only d. protons and electrons

c: protons and neutrons

Which of the following statements is NOT true? a. Atoms of the same element can have different masses. b. Atoms of isotopes of an element have different numbers of protons. c. The nucleus of an atom has a positive charge. d. Atoms are mostly empty space.

c: the nucleus of an atom has a positive charge

Dalton's theory essentially agreed with the present atomic theory EXCEPT for the statement that a. all matter is made up of small particles called atoms. b. atoms are not divided in chemical reactions. c. atoms of the same element are chemically alike. d. all atoms of the same element have the same mass.

d. all atoms of the same element have the same mass.

a negatively charged subatomic particle

electron