4.2 – NOTES The Mass of the Atom

Slides:

Advertisements

Similar presentations

Isotopes and Mass Number. Atomic Number The number of protons in each atom identifies it as an atom of a particular element Each atom has a unique number.

Advertisements

Dalton was proved incorrect and his theory was modified

Counting Atoms.

Ch. 3 - Atomic Structure II. Masses of Atoms (p.75-80) Mass Number

Atomic Structure I. Subatomic Particles.

Mass Number Atomic Number equals the # of... NUCLEUS ELECTRONS PROTONS NEUTRONS NEGATIVE CHARGE POSITIVE CHARGE NEUTRAL CHARGE ATOM.

Isotopes Average Atomic Mass. Isotopes  Atoms of the same element (same atomic number) with different mass numbers  Atoms with the same number of protons,

NOTES – 4.3: Atomic Number, Mass Number, Isotopes and Atomic Mass.

More about isotopes Atomic mass vs average atomic mass or atomic weight.

Ch. 3 - Atomic Structure II. Masses of Atoms (p.75-80)  Mass Number  Isotopes  Relative Atomic Mass  Average Atomic Mass.

Atomic Mass. Masses in amu Only carbon-12 has an atomic mass exactly equal to its mass # One atomic mass unit (amu) is defined as 1/12 the mass of a carbon-12.

Isotopic Abundance SCH 3U. Atomic Mass The mass of an atom (protons, neutrons, electrons) Relative Atomic Mass: An element’s atomic mass relative to the.

Atomic Structure.  Atomic number – the number of protons in the nucleus of an atom ( ID of element )  Mass number– sum of protons and neutrons in an.

Section 4.3 How atoms differ. Atomic Number Represents three things in a neutral atom: 1. What element it is 2. The number of protons in each atom 3.

Atomic Structure The Periodic Table, Isotopes, and Average Atomic Mass.

Isotopes. The Nucleus  The number of protons in the nucleus of an atom is unique to each type of element  BUT, the nuclei of the same type of element.

Unit 3: Atomic Structure. A. Subatomic Particles Most of the atom’s mass (Mass Number) NUCLEUS ELECTRON CLOUD PROTONS NEUTRONS ELECTRONS POSITIVE CHARGE.

Isotopes. Let’s Review ProtonsNeutronsElectrons Charge +1 0 Mass 1 amu 0 Location nucleus Electron cloud.

Isotopic Abundance Pages Thinking question Why are there decimal places for atomic masses on the periodic table if protons and neutrons have amu.

1 The Atom Atomic Number and Mass Number Isotopes.

Isotopes are atoms of the same element that have a different number of neutrons For example, Hydrogen has 3 isotopes: Protium (0 neutrons) Deuterium (1.

Protons, Neutrons and Electrons

SNC1D Isotopes.

Basic Atomic Structure

Atomic Structure Current Atomic model

Ch. 3-3a Distinguishing and Counting Atoms

Counting Atoms.

II. Masses of Atoms Mass Number

Average Atomic Mass In nature, most elements are a mixture of different isotopes The mass of a sample of an element is a weighted average of all the isotopes.

Calculating Average Atomic Mass

Calculating Average Mass

Basic Atomic Structure

Warm Up Monday 1/25/16 1. What are atoms?

Atomic Structure Subatomic Particles C. Johannesson.

Subatomic Particles Masses of Atoms Mass Number Isotopes Ions

Atomic Structure.

Isotopes and RAM Learning Outcomes:

ISOTOPES AVERAGE ATOMIC MASS

Counting Atoms Section 3.3.

Unit 2: Atomic Theory & Structure

The atom and Isotopes.

Subatomic Particles.

Atomic Symbols protons + neutrons = mass # atomic # = protons.

Ch Atomic Structure II. Masses of Atoms (p.30-31) Mass Number

ISOTOPIC NOTATION isotopes are atoms with the same number of protons but different number of neutrons A Z X A = mass number (the total number of protons.

Distinguishing Between Atoms

Atomic Structure.

H H H Isotopes element: same or different mass:

Structure of The Atom Not the Adam.

H H H Isotopes element: same or different mass:

Warm Up What are the particles that make up the atom?

Counting Atoms.

Mass of Individual Atoms

Subatomic Particles.

Ch. 3 Atoms 3.3 Counting Atoms.

Atoms – a closer look at elements

Atomic Symbols protons + neutrons = mass # atomic # = protons.

Ch. 3 - Atomic Structure II. Masses of Atoms (p.75-80) Mass Number

Element properties & isotopes

Atomic Symbols = = mass # atomic # protons + neutrons protons

Atomic Symbols protons + neutrons = mass # atomic # = protons.

Atomic Number, Mass Number, Atomic Mass and Isotopes

Goals To define ions and isotopes

Ch. 4 - Atomic Structure II. Masses of Atoms Ch.4 Mass Number Isotopes

Basic Atomic Structure

Ch. 4 - Atomic Structure II. Masses of Atoms Mass Number Isotopes

ARE ALL ATOMS OF THE SAME ELEMENT IDENTICAL?

Subatomic Particles.

Atomic Particles Particle Charge Mass (kg) Location Electron -1

Presentation transcript:

4.2 – NOTES The Mass of the Atom

III. How atoms differ A. Atomic Number Equal to the number of protons – never changes; equals the number of electrons if AND ONLY IF the atom is neutral; Moseley discovered each atom has a unique number of protons in the nucleus;

B. Isotopes and mass number 1. Definition of isotopes: atoms of the same element with differing numbers of neutrons; H has 3 isotopes – protium (1 proton) deuterium (1 proton and 1 neutron) tritium (1 proton and 2 neutrons); usually have similar properties, but can have specific uses like C-14 (carbon dating); most elements are found as a mixture of their isotopes

2. Mass number: represents the total number of protons and neutrons; specific to each isotope (U-238 vs U-235); #n0 = mass # - atomic #; does not include mass of electron b/c mass of electron is ~2000x less than that of proton and/or neutron

3. Nuclear symbols and nuclides: nuclide – specific atom with a mass number attached (Li-7); Mass # Atomic symbol atomic # = nuclear symbol; Examples: 1H1 = protium (H isotope); 2H1 = deuterium; 3H1 = tritium H – 1; H – 2; H – 3;

C. Mass of individual atoms 1. Atomic mass units (amu) – the mass of a single proton or neutron is too small to use easily - scientists developed a method to measure the mass of an atom relative to an atomic standard – carbon 12; 1 amu = 1/12 the mass of a carbon-12 atom; the value of 1 amu and that of a proton are slightly different; explains why Si-30 is really 29.974

2. Atomic weights on the periodic table are weighted averages.

Mg is a good example: 78. 99% is Mg-24 has a mass of 23. 985amu, 10 Mg is a good example: 78.99% is Mg-24 has a mass of 23.985amu, 10.00% is Mg – 25 with a mass of 24.986 and 11.01% is Mg-26 with a mass of 25.982. What is the average weight? Any element’s average mass can be calculated if the # of isotopes, mass of each isotope and relative abundance of each isotope is known. **% should be put in decimal form. Average mass = (%)(mass) + ( %)(mass) + … Mg – 24: (0.7899)(23.985) = 18.95 Mg – 25: (0.1000)(24.986) = 2.499 Mg – 26: (0.1101)(25.982) = 2.861 24. 310 = 24.31 amu

Sample Problems: 1. The abundance of B-10 is 19.78% and has a mass of 10.011amu. The abundance of B-11 is 80.22% with a mass of 11.009amu. Determine the atomic weight of boron: B – 10: (0.1978)(10.011) = 1.980 B – 11: (0.8022)(11.009) = 8.831 10.811 amu

2. Chlorine has 2 isotopes: Cl-35 and Cl-37 2.Chlorine has 2 isotopes: Cl-35 and Cl-37. Since the atomic weight of Cl is about 35.5, what are the approximate relative abundances of these isotopes? Easiest way to solve this problem is to make a number line. KEEP IN MIND – this is a weighted average! What that means is since the average (35.5) is closer to Cl-35, Cl-35 is more abundant (= larger percentage); in this problem, the percentages are 25% and 75% so Cl- 35 must be 75% of the abundance